Fixed bug with nonce check failing for forms with integer values

This was because integer values were being converting to strings during form submission & when sorted before building the nonce action string, were being sorted the wrong way.
Converting the integer to a string before the initial action string is build solved this problem.
Fixed frm_action field from being rendered twice.

Removed adding of frm_action field separately, as now included in the protected fields properties so is rendered with them.
Added method to instantiate a normal CM_WP_Module_Mustache_Context object