Moved rest from cache to mongo, and some refactoring.

* Changes to DotaApi class to store players in db instead of using cache.
* Removed the Cache class as it is no longer used.
* Changed getPlayerSummary to require a valid steam id instead of trying to parse each time.
* Added a new api method /api/players/resolveId/:playerId used to resolve non-community steam ids.
* Changed updatePlayerBySteamid in Database to be create=false by default.
Changes to front-end to make use of resolveId.