Merge branch 'bc/git-p4-for-python-2.4'

With small updates to remove dependency on newer features of Python, keep git-p4 usable with older Python. * bc/git-p4-for-python-2.4: INSTALL: git-p4 does not support Python 3 git-p4.py: support Python 2.4 git-p4.py: support Python 2.5