Parse __version__ from __init__.py

This way we don't crash if dependencies aren't installed.

License assent:
    https://github.com/zulip/python-zulip/pull/3#issuecomment-18182458

(imported from commit f1aa37e97c60a06234c004ada48e08984a085d6f)

setup.py

@@ -5,6 +5,17 @@ import zulip
 
 import os
 from distutils.core import setup
+import sys
+
+import itertools
+
+def version():
+  version_py = os.path.join(os.path.dirname(__file__), "zulip", "__init__.py")
+  with open(version_py) as in_handle:
+    version_line = itertools.dropwhile(lambda x: not x.startswith("__version__"),
+                                       in_handle).next()
+  version = version_line.split('=')[-1].strip().replace('"', '')
+  return version
 
 def recur_expand(target_root, dir):
   for root, _, files in os.walk(dir):
@@ -13,7 +24,7 @@ def recur_expand(target_root, dir):
       yield os.path.join(target_root, root), paths
 
 setup(name='zulip',
-      version=zulip.__version__,
+      version=version(),
       description='Bindings for the Zulip message API',
       author='Zulip, Inc.',
       author_email='zulip@zulip.com',