Periodically check goals status.

- Store goal description in mongodb.
- Poll interval is 10 minutes (+- 2 mins at random to avoid spikes)
- Broke Github hooks unit-tests
Skip GitHub unittests
Save user achievements. Codeforces goal is actually works now.
Add dependency on pymongo
Add dummy index.html
Fixed test
Factored user_goals to a separate method
Method to check current status of goals
Removed Github hooks.

While push model has its advantages, it does require editing GitHub
configuration. This is inconvient, so we are going to switch to pull
model on top of GitHub API.
GET /status/{user} returns actual results