Ensure that we only create the frame path once and then update it, rather than create a new one every time, otherwise matplotlib uses old clip paths when plotting objects.
Added images regression tests for frame clipping
Added changelog entry
Temporarily disable Numpy 1.5/Matplotlib 1.2 tests
Merge pull request #113 from cdeil/ah-update

Update astropy_helpers sub-module pointer to v0.4.2
Merge pull request #117 from astrofrog/fix-frame-path

Patch needs to be updated as soon as it is accessed
Update
Add license line and clean up imports a bit