version bump to 1.7.7-dev

I expect the next release to actually be 1.8, but to prevent issues
if we decide to release 1.7.7, I'm only moving the rev number.

Change-Id: Ia9e05c5f036b8fbf67972470f240e84f7595223a

swift/__init__.py

@@ -14,7 +14,7 @@ def pretty_version(self):
             return '%s-dev' % (self.canonical_version,)
 
 
-_version = Version('1.7.6', False)
+_version = Version('1.7.7', False)
 __version__ = _version.pretty_version
 __canonical_version__ = _version.canonical_version