Fixed saving on Input Parameters for Automate Method.

- Fixed to set/save default value for datatype of an Automate Method Input field to be 'string'.
- Fixed saving of input parameters when adding a new Method.

https://bugzilla.redhat.com/show_bug.cgi?id=1161761
https://bugzilla.redhat.com/show_bug.cgi?id=1161701

@dclarizio please review/test.