feat: /leaderboard endpoint

Now directly sorts by commit, for specified number of projects in
toystory.conf. All calls are made asynchronously through aiohttp,
which in turn uses asyncio.
fix: requirements

added asyncio and aiohttp
update: README

asyncio and aiohttp are py3.3+
Merge remote-tracking branch 'upstream/master' into github

Conflicts:
	api/toystory/storage/base/__init__.pyc
	api/toystory/storage/base/driver.pyc
	api/toystory/storage/memory/controllers.pyc
	api/toystory/storage/memory/driver.pyc
Merge pull request #12 from TheSriram/github

Leaderboard Endpoint