Add casting restrictions; Let Annotation.resume receive same parameters as .new

Change Log for 0.0.8

Add casting restriction

Impact: This update requires changes to your code for all properties that now have :cast = false.

Affected properties:

• motivatedBy
• annotatedAt
• content
• format

Required change in your code for motivatedBy:
Assumptions:

• anno is an instance of Annotation or a subclass

OLD:  anno.motivatedBy.first.rdf_subject
NEW:  anno.motivatedBy.first 

Allow Annotation.resume to receive same argument values as Annotation.new

Annotation.resume now accepts the following values for its parameter.

• RDF::URI - e.g. RDF::URI('http://example.org/t123') -- this is the only value accepted prior to this change
• string URI - e.g. 'http://example.org/t123'
• localname - e.g. 't123' -- This will be expanded by appending 't123' to the end of the configured base_uri