Added Maxlength Attribute Definition to the Textarea AttributeType for Coanda CMS
Changed Maxlength Attribute Definition for Textarea AttributeType to a string from array
Added method for processing Attribute Property which returns either a string or an array to PageType
Merge pull request #5 from AdenFraser/master

Max length added to the textarea attribute.
Also, updates to the PageType so that attribute properties can be strings or arrays.