[PATCH 0 of 5 RFC] Command Server POC

[Idan Kamara]

Here's the first queue of the command server, it is still in early stages but
I think I have enough to get some feedback.

included:
- new option --cmdserver to serve
- a small Python wrapper, hglib, around the server that can connect to a repository
and run commands. Also included is a sample of how real hg commands might
look like in the lib, see status().
- a shell that uses hglib and runs commands against a given repository
- last 2 patches are an attempt to integrate the command server to the test suite.

known issues:
- I haven't dealt with outside changes to the repository yet, so the internal repo in the server can go out of sync.
- see the last 2 patches for some hacks and other known issues with the testsuite.