* Create a Request class which maintains its own connection pool
* When creating a Bot instance a new Request instance will be created if one wasn't supplied.
* Updater is responsible for creating a Request instance if a Bot instance wasn't provided.
* Dispatcher: add method to run async functions without decorator
* Dispatcher can now run as a singleton (allowing run_async decorator to work) as it always did and as multiple instances (where run_async decorator will raise RuntimeError)
* initial commit for conversationhandler and example
* implement simple Promise for run_async/conversationhandler
* refactor Promise._done to done
* add handling for timed out Promises
* correctly handle promises with None results
* fix handling tuple states
* update comments on example
* Added a first test on the ConversationHandler.
* Fixed a small typo.
* Yapf'd.
* add sphinx doc for conversation handler
* fix title for callbackqueryhandler sphinx docs
