use regexp to parse the mailmap

this also makes parse_mailmap() work with the swift .mailmap and should
be more readable

Change-Id: I3abb2a18d655e507bee5f621ebc64421d943cf0b
Stop using no longer valid -E option for pip

Fixes bug 1100403

Version 1.1 of pip dropped the -E option. It's not necessary anyway since
running pip in a correctly setup virtualenv will automatically do the right
thing.

Change-Id: Ifec9f27b8dc169d594125a0808126abe77ed42e7
Merge "use regexp to parse the mailmap"