First step in two-part process to rename directories to kallithea.
This first step is to change all references in the files where they refer
to the old directory name.

synced vcs with upstream

- moved subprocessio module to VCS
- many small changes to make embedded vcs as similar to to external lib
- use only absolute imports
- patch vcs config during load pylons env

Implemented generation of changesets based
on whole diff instead of per file diff. That
can give a big speed improvement for large changesets in
repositories with large history.
- improved handling of binary files
- show renames of binary files
- implemented new diff limit functionality
- unify diff generation between hg and git
- Added binary indicators for changed files,
- added diff lib tests

Added vcs testsuite for better integration tests + added fetching
of two new repos into test env for rhodecode