Fix setuptools package resources

https://pythonhosted.org/setuptools/setuptools.html#including-data-files

MANIFEST.in

@@ -1 +1,6 @@
-recursive-include letsencrypt/ *
+recursive-include letsencrypt *.json
+recursive-include letsencrypt *.sh
+recursive-include letsencrypt *.conf
+recursive-include letsencrypt *.cnf
+include letsencrypt/client/ca_offerings
+include letsencrypt/client/.ca_offerings

letsencrypt/client/acme.py

@@ -4,8 +4,10 @@
 # validate JSON objects as ACME protocol messages
 
 import json, jsonschema
+import pkg_resources
 
-schemata = {schema: json.load(open("letsencrypt/client/schemata/%s.json" % schema)) for schema in [
+schemata = {schema: json.load(open(pkg_resources.resource_filename(
+    __name__, "schemata/%s.json" % schema))) for schema in [
   "authorization", "authorizationRequest", "certificate", "certificateRequest",
   "challenge", "challengeRequest", "defer", "error", "revocation",
   "revocationRequest", "statusRequest"]

setup.py

@@ -29,4 +29,6 @@ setup(
             'letsencrypt = letsencrypt.scripts.main:main'
         ]
     },
+    zip_safe=False,
+    include_package_data=True,
 )