Remove recenter functionality from map.rotate()
Change units and direction of rotation
Update the metadata for the rotated coordinate system
Proper rotation of rectangular maps
Update the rotation angle in the metadata, and use by default
Re-implemented recenter functionality
map.rotate() docstring tweaks
Updated map.rotate() tests
Only update the CROTA2 keyword if it already exists
Some PEP8 fixes pulled from another PR to ease merging
Fix existing call to map.rotate()
Convert input rotation matrix to an array
Update CHANGELOG
Merge pull request #1026 from ayshih/rotate-0.4

`map.rotate()` fix for 0.4.1