removed is_file from from in create_flag

This forces an error if no value is returned (if the box is not checked
this will happen).  With the current logic, this is taken care of with
__mkflag__ so is unneeded here, and allows creations of flags that are
not files.
html passed value changed form yes to true

This may be unneeded but it now follows the logic in __mkflag__
Merge pull request #4 from Enki--/master

fixed if_file issue