Delete supported params

1) Supported params list deleted, because it's hard to keep it fresh (there was cool parser by davidjb, but it does not take care of underscores and hiphen in options names). Now all parameters considering supported, and all hiphen will be replaced with underscore when salt creates my.cnf. Thats why all default parameters changed to underscore type.
2) Fixed bug with empty config append parameter
3) Fixed bug with empty root password applying