Modernize Git to upstream GitRepos, mainly command handling.
* Convert to use proc_open and COM for command interfacing. This allows
us to retrieve stdout seperate from stderr, as well as use stdin.
* Implement extended output options. Might be a little buggy, so needs
testing.
* Remove --git-dir; directory information is transmitted via execution.
* Fix E_NOTICE in Git_Commit
* Add Git_Exception_Command
* Revamp Git_Repo->__construct to recursively search upwards for Git. This
greatly improves the flexibility of paths we can pass.
* Fix bug with path arrays in Git_Repo->log()
* Turn on error reporting in the sample.php file
* Smoosh single character args, so -s our becomes -sour
Signed-off-by: Edward Z. Yang <edwardzyang@thewritingpot.com>