Updated Readme to support new tracking mixin
Optimized django queryset use
Changed to deal better with None values
Add minor change to updated docs
Remove unused variables
Merge branch 'saulshanabrook-feature/query-optimizations'
Clean up some typos
Merge branch 'saulshanabrook-fix/url-returns'
Add coveralls to CI testing
Merge pull request #10 from elbaschid/feature/integrate_coverall

Add coverage to CI testing using coveralls.io
Check for a blank old_url before creating delete

This way it won't go through the trouble of creating a UrlChangeRecord if the old_url is blank (new object) or the url is unchanged
Merge pull request #11 from saulshanabrook/patch-1

Check for a blank old_url before creating delete
Add myself to authors

:)
Merge pull request #12 from saulshanabrook/patch-2

Add myself to authors