Add __version__ to init file

tests/test_version.py

@@ -0,0 +1,8 @@
+import toot
+from pkg_resources import get_distribution
+
+
+def test_version():
+    """Version specified in __version__ should be the same as the one
+    specified in setup.py."""
+    assert toot.__version__ == get_distribution('toot').version

toot/__init__.py

@@ -2,6 +2,8 @@
 
 from collections import namedtuple
 
+__version__ = '0.16.2'
+
 App = namedtuple('App', ['instance', 'base_url', 'client_id', 'client_secret'])
 User = namedtuple('User', ['instance', 'username', 'access_token'])