Fix wrong doc string for meter type

Meter type can be (gauge, delta, cumulative), not (gauge, counter).
This patch also fixes a typo s/extention/extension/.

Change-Id: I11d7fcefe0ec40afbf9ecc976cb65752600ea1c0
Drop foreign key contraints of alarm in sqlalchemy

This patch drops the foreign key constraints of alarms to user_id and
project_id in sqlalchemy.

Closes-Bug: 1260176
Change-Id: I7336ee1e3f885421db5aae3a30af0e918b79450b
Merge "Fix wrong doc string for meter type"
Merge "Drop foreign key contraints of alarm in sqlalchemy"