get default configuration for an instance
listing instances only shows active instances that the configuration is linked to
created an overrides template for mysql
pass down the overrides as a file to be written instead of a dictionary

Change-Id: I3921587b656c33f3db4d630f1475c0701ca50c92
adding the template for overrides in mysql

Change-Id: If540c121e55ec77ab3f8ed45eb64adc32a6ce597