Migration to new datastore, python 2.7 and webapp2

Migration of the app to the high replication datastore after the
deprecation of the master/slave datastore.

List of changes:
- Changed app id.
- Removed all external libraries libs folder.
- Migrated tipfy handlers to webapp2 handlers.
- Upgraded db to ndb.
- Upgraded to Python 2.7 api.
- Removed all login and user specific code.