have letsencrypt.VERSION, show it in letsencrypt --help, use it in setup.py

note: we had some discussion about potential problems importing VERSION from main package.

SO link: http://stackoverflow.com/questions/2058802/how-can-i-get-the-version-defined-in-setup-py-setuptools-in-my-package

See also my comment in __init__.py - maybe we can add that "version detection from git tags" magic later.

letsencrypt/__init__.py

@@ -1 +1,10 @@
 """Let's Encrypt."""
+
+# do not import stuff here. this file is used by setup.py, thus importing
+# stuff here might break setup.py as dependencies are not installed yet.
+
+VERSION_TUPLE = 0, 1, 0, "a0"
+"""version tuple: major, minor, micro, {a|b|rc}N - see PEP440"""
+
+VERSION = "%d.%d.%d%s" % VERSION_TUPLE
+"""version as str"""

letsencrypt/scripts/main.py

@@ -8,6 +8,7 @@ import sys
 import zope.component
 import zope.interface
 
+from letsencrypt import VERSION
 from letsencrypt.client import CONFIG
 from letsencrypt.client import client
 from letsencrypt.client import display
@@ -19,7 +20,7 @@ from letsencrypt.client import log
 def main():  # pylint: disable=too-many-statements,too-many-branches
     """Command line argument parsing and main script execution."""
     parser = argparse.ArgumentParser(
-        description="An ACME client that can update Apache configurations.")
+        description="letsencrypt client %s" % VERSION)
 
     parser.add_argument("-d", "--domains", dest="domains", metavar="DOMAIN",
                         nargs="+")

setup.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 from setuptools import setup
 
+from letsencrypt import VERSION
 
 install_requires = [
     'argparse',
@@ -31,7 +32,7 @@ testing_extras = [
 
 setup(
     name="letsencrypt",
-    version="0.1",
+    version=VERSION,
     description="Let's Encrypt",
     author="Let's Encrypt Project",
     license="",