Fix username case in auth.getMobileSession() and use DBMS's lower().
Fix username case in auth.getMobileSession() and use DBMS's lower().

auth.getMobileSession() should use lowercase usernames in its authToken
hash calculation. Now users with uppercase letters in their names can
get sessions.

foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm,foocorp/gnu-fm