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.
Merge branch 'master' into feature/refactor-local-maps
Adds docstrings to maps.py
Adds error messages to exceptions in maps.py
Merge branch 'master' into feature/refactor-local-maps

Conflicts:
	distarray/tests/test_decorators.py
Merge pull request #260 from enthought/feature/refactor-local-maps

Refactors local maps
Fixes grid_shape-related bug in LocalArray.from_dim_data.
Add the validator from the Distributed Array Protocol.