Added second plan 1gb to MySQL broker

- creates management database for mapping service instances to plans
- mgmt db is populated with the existing service instances using
  the first plan in the catalog
- migration is executed only on the first broker node
- extended the acceptance tests to run create/bind/unbind/delete for
  instances of all plans
- renamed mgmt db from test to mysql_broker

[#66627936]

Conflicts:
	config/initializers/omniauth.rb