Use InnoDB for MySQL

This change adds a migration to convert any non-InnoDB tables to
InnoDB.

On some systems, the default engine is MyISAM, which doesn't
support features used by Keystone (foreign keys).

The approach is the same as what's used in Nova. A test is added
to ensure that all tables use InnoDB after migration. The test
passes when all the tables are mysql_engine='InnoDB'. This is
accomplished by adding a new migration that migrates all the
tables that aren't InnoDB to InnoDB.

Fixes bug 1191110.

Change-Id: I220f7642f5468c5cf4194f248210f90ff983b6e5
Merge "Use InnoDB for MySQL"