Feature: allow user to type divisor

[jmvalencia]

Set a flag attribute that allows user to type the divisor bye them-self not automatically.

[madmoizo]

+1

If the divisor match with the mask, there is no reason to reject it

[madmoizo]

my proposal https://github.com/candreoliveira/ngMask/issues/86 can override this one (maybe..) depending of what is the easiest to do