Update mm_util.py: metadata JSON loading

create mm_util.get_default_metadata_data() and
mm_util.get_child_metadata_data() to load metadata JSON centrally,
replace references in the project to the file name with this function.
Update mm_project.py: refresh() fix

Fix for https://github.com/joeferraro/MavensMate/issues/6

Checks for project root or /src directory to refresh all metadata, if not checks that metadata type could be found before adding it to the refresh list.

Update hard reference to metadata json with mm_util.get_default_metadata_data()
Merge pull request #2 from doublesharp/patch-3

Update mm_project.py: refresh() fix
Merge pull request #7 from doublesharp/patch-2

Metadata JSON loading and refresh() fix