Release 0.5.2.
Roll back README.md->rst rename.
Cleanup use of Binding.

- Use namedtuple for Binding class.
- Use Binding instead of a raw tuple in function annotations.
Add CallError exception class to better show why injection/instantiation fails
Fix ClassError.__str__ bug and make it's message cleaner
Make CallError message contain class instance repr() rather than class name
Create few CallError-related tests
Create AssistedFactoryProvider
Fix one cosmetic readme issue
Fix whitespace in readme
Fix CallError for Python 3
Merge pull request #5 from jstasiak/master

Add CallError exception class to better show why injection/instantiation fails
Merge branch 'master' into assisted-injection

Conflicts:
	injector.py
	injector_test.py
SImplify assisted injection API
Update readme to match modified assisted injection API
Merge pull request #6 from jstasiak/assisted-injection

Implement assisted injection.
Tune readme a little
Fix readme doctest
Ok, really fix the readme doctest now
Merge pull request #8 from jstasiak/master

Update AssistedBuilder details in README.