Big commit sorry

Mecanism to retrieve/add some data from RideMSpotAPI :
-List of comment from spot (by spot id)
-List of spot (get favorite by his user id)
-Get user data if he is already register on the api or resgister him
instead
-Add/Remove from favorite
-Add comment
-Add spot

Add the session manager which manage the user credential by the
sharedPreference

Add some class to manage the oauth google token (not in use for the
moment)

Add a splashscreen interface when retrieving user credential from his
google mail

Add the entity file from generated appengine plugins