Removed unnecessarily populating args list with null values

With the introduced usage of Inject::inst()->createWithArgs, we no longer need
to populate the args list with empty and can just rely on what the user provides

This means that the ::textarea method can be removed, and we now support the
use of password field without throwing an deprecation warning.
Merge pull request #3 from clairefinnie/fix-for-password

Removed unnecessarily populating args list with null values