Implements Traits for Shared Partial Forms

[doylejd]

Resolves issue #35

• Remove form definitions from AddThis.php and refactor them as Traits.
• Updated AddThisBlock.php to use the new traits.
• Updated Field Formatters to use the new traits.
• Updated Block submit to be more dynamic using the traits.

[nerdstein]

Missing validation

[nerdstein]

Block and Field forms looking to use Traits

[doylejd]

Resolved validation issues.