fix shebangs

If possible, could you fix the python shebangs in "src/bitmessagemain.py" and
"src/bitmessagecli.py"?
Our shebang fixer did not stumble on more, but if you had more like those two they could get fixed too.
`#!/usr/bin/env python2.7.x'`#!/usr/bin/env python2.7' should get fixed in my opinion.

If you regard it as not necessary, could you please explain why.
