Hiding fields and simple templates overrides

Features

Added hide property on fields. Allows devs to conditionally show fields. Also adding hideExpression property which is an expression that will be evaluated on the result object (using $parse) to make the api simpler to use.

Added template property on fields. Allows devs to have one-liner templates. Mainly used for directives so a single template can be used with options. Also improved the id of fields that use templateUrls or templates.