Issue #12: Add mutually exclusive options -r/--remote and --all-remotes to branch health command line argument processing.
(No Issue): Move getBranchMapSortedByDate out of private methods in manager.py.
Issue #12: Refactor logic for whether to get branch map from remote or locally into manager object.
Issue #12: Rename BranchManager.__getLocalBranchMap() to getBranchMapFromRefList, so it better describes the function.
Issue #12: Refactor manager object to move sorting into getBranchMap() instead of being in the branch health application object.
Issue #12: Add functionality for --all-remotes switch based on a composition of other branch map retrieval functionality.