Implement Gitopia node #6

Gitopia node will serve the following purposes:

• Transaction posting server: In order to make on-boarding easier for the users, user can use Gitopia freely upto a certain limit and the transaction posting server will bear the cost.
• Serving loose git objects for lazy loading of git objects
• Serving aggregated packfile to git clients

In the future release, staking and slashing mechanisms will be designed to encourage people to run community run Gitopia nodes.