Fix warnings
RFC: We send the SHA1 of the public key with authenticate requests not the whole key (to save space)
appengine: add google's appengine maven plugin as that has a nicer devserver for debugging - we get logs - not useful for automated tests though
appengine: clean up error messages in NigoriServlet
server:core: Do more loggin in DatabaseNigoriProtocol so that we don't miss any useful stacktraces