make self_test not import if pytest is not installed
Change Map methods from returning a new map to a modified copy
change to deepcopy to make a copy of meta
put pytest import inside main() function
actually remove the top level pytest import...
Merge pull request #668 from Cadair/map_rot_fix

Change Map methods from returning a new map to a modified copy
move import out of function while maintaining behaviour
Merge pull request #739 from Cadair/pytest_patch

self_test will throw an ImportError if pytest is not installed
Merge branch 'master' of https://github.com/sunpy/sunpy