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