mysql: Un-pin Puppetlabs MySQL module, update for >= 2.2

According a recent thread on puppet-openstack mailing list[1], we planed
to drop puppetlabs/mysql 0.x support for Juno release. Our module is
pined to 0.x branch because >= 2.2 break retro-compatibility. This
commit update puppet-openstack-cloud to the latest version of
puppetlabs/mysql.

[1] https://groups.google.com/a/puppetlabs.com/d/topic/puppet-openstack/8xJ-XtBa_C0

manifests/orchestration.pp

@@ -137,6 +137,7 @@ class cloud::orchestration(
     keystone_password => $ks_heat_password,
     auth_uri          => "${ks_keystone_internal_proto}://${ks_keystone_internal_host}:${ks_keystone_internal_port}/v2.0",
     sql_connection    => "mysql://${encoded_user}:${encoded_password}@${heat_db_host}/heat?charset=utf8",
+    mysql_module      => '2.2',
     rabbit_hosts      => $rabbit_hosts,
     rabbit_password   => $rabbit_password,
     rabbit_userid     => 'heat',