Load configuration from the project's central repository

[zostay]

As a followup to issue #1, we should be able to load the configuration from project itself while it is still on the server. This can hep alleviate the challenge of not having the configuration during gitc-setup, but presents a some new problems on it's own:

1. What security implications could this have? Probably this is relatively safe since we'd only do it in cases where you have requested to setup a project or where it is enabled, but any time you grab something from a network and make decisions based upon what you find, security must be examined.
2. Do we want to try this normally? Do we enable it or prefer it in some repositories? For example, should there be a use_server_config setting in the $PROJECT/.gitc/gitc.config to enable this? Should it be enabled by default? Should there be a command-line option for enabling/disabling it during gitc-setup or other operations?
3. The time at which this config is probably most useful is during gitc-setup, so we'll need to make it so that it is possible to send gitc-setup a full git repository path and load the configuration at whatever location we find.

[SineSwiper]

This is tied to #33.