Added apache2 dav and dav_svn modules to debian_apache_2_4 two_vhost_80 test data.

Also added symlinks in mods-enabled to the newly added files to include
the modules in the test.
After doing so, many tests fail with "AttributeError: 'NoneType' object has no attribute 'lower'"
in letsencrypt_apache/parser.py", line 311.

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-available/authz_svn.load

@@ -0,0 +1,5 @@
+# Depends: dav_svn
+<IfModule !mod_dav_svn.c>
+    Include mods-enabled/dav_svn.load
+</IfModule>
+LoadModule authz_svn_module /usr/lib/apache2/modules/mod_authz_svn.so

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-available/dav.load

@@ -0,0 +1,3 @@
+<IfModule !mod_dav.c>
+	LoadModule dav_module /usr/lib/apache2/modules/mod_dav.so
+</IfModule>

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-available/dav_svn.conf

@@ -0,0 +1,56 @@
+# dav_svn.conf - Example Subversion/Apache configuration
+#
+# For details and further options see the Apache user manual and
+# the Subversion book.
+#
+# NOTE: for a setup with multiple vhosts, you will want to do this
+# configuration in /etc/apache2/sites-available/*, not here.
+
+# <Location URL> ... </Location>
+# URL controls how the repository appears to the outside world.
+# In this example clients access the repository as http://hostname/svn/
+# Note, a literal /svn should NOT exist in your document root.
+#<Location /svn>
+
+  # Uncomment this to enable the repository
+  #DAV svn
+
+  # Set this to the path to your repository
+  #SVNPath /var/lib/svn
+  # Alternatively, use SVNParentPath if you have multiple repositories under
+  # under a single directory (/var/lib/svn/repo1, /var/lib/svn/repo2, ...).
+  # You need either SVNPath and SVNParentPath, but not both.
+  #SVNParentPath /var/lib/svn
+
+  # Access control is done at 3 levels: (1) Apache authentication, via
+  # any of several methods.  A "Basic Auth" section is commented out
+  # below.  (2) Apache <Limit> and <LimitExcept>, also commented out
+  # below.  (3) mod_authz_svn is a svn-specific authorization module
+  # which offers fine-grained read/write access control for paths
+  # within a repository.  (The first two layers are coarse-grained; you
+  # can only enable/disable access to an entire repository.)  Note that
+  # mod_authz_svn is noticeably slower than the other two layers, so if
+  # you don't need the fine-grained control, don't configure it.
+
+  # Basic Authentication is repository-wide.  It is not secure unless
+  # you are using https.  See the 'htpasswd' command to create and
+  # manage the password file - and the documentation for the
+  # 'auth_basic' and 'authn_file' modules, which you will need for this
+  # (enable them with 'a2enmod').
+  #AuthType Basic
+  #AuthName "Subversion Repository"
+  #AuthUserFile /etc/apache2/dav_svn.passwd
+
+  # To enable authorization via mod_authz_svn (enable that module separately):
+  #<IfModule mod_authz_svn.c>
+  #AuthzSVNAccessFile /etc/apache2/dav_svn.authz
+  #</IfModule>
+
+  # The following three lines allow anonymous read, but make
+  # committers authenticate themselves.  It requires the 'authz_user'
+  # module (enable it with 'a2enmod').
+  #<LimitExcept GET PROPFIND OPTIONS REPORT>
+    #Require valid-user
+  #</LimitExcept> 
+
+#</Location>

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-available/dav_svn.load

@@ -0,0 +1,7 @@
+# Depends: dav
+<IfModule !mod_dav_svn.c>
+    <IfModule !mod_dav.c>
+        Include mods-enabled/dav.load
+    </IfModule>
+    LoadModule dav_svn_module /usr/lib/apache2/modules/mod_dav_svn.so
+</IfModule>

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-enabled/authz_svn.load

@@ -0,0 +1 @@
+../mods-available/authz_svn.load

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-enabled/dav.load

@@ -0,0 +1 @@
+../mods-available/dav.load

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-enabled/dav_svn.conf

@@ -0,0 +1 @@
+../mods-available/dav_svn.conf

letsencrypt-apache/letsencrypt_apache/tests/testdata/debian_apache_2_4/two_vhost_80/apache2/mods-enabled/dav_svn.load

@@ -0,0 +1 @@
+../mods-available/dav_svn.load