Update Catalyst.pod

Adding a necessary `use` line to the controller example code.
Update Intro.pod

Correcting the capitalization of the TextArea type.
Update Validation.pod

Making a few clarifications regarding the 'when' hashref and the 'required_when' and 'validate_when_empty' field attributes.
Merge pull request #39 from jmacdotorg/master

Several ::Manual doc patches