Change LocalArray indexing to be global.

Global indexing is at global_get/setitem
Reflect changes to LocalArray indexing in DistArray
PEP8 localarray.py
Renames IndexMap.__init__ in prep for refactoring.
Adds maps.MDMap class to manage maps for LocalArrays.
Remove comment.
Replaces IndexMap with class heirarchy.
Gets testsuite working with new local maps.
Completely removes IndexMap class (and auxiliary functions).
Small cleanup and formatting in maps.py
Map tests test global_from_local(), not global_index.
test_maps tests local_from_global(), not local_indices.
Contain global_index and local_index in properties.
Replaces global_index with global_iter on Map classes.
Removes local_index from Map classes.
Cleanup tweaks.
PEP8 E265 "block comments should start with a '# '"
Merge branch 'master' into feature/refactor-local-maps
Merge pull request #261 from cowlicks/pep8-E263

PEP8 E265 "block comments should start with a '# '"
Adds docstrings to maps.py