Update Object, add some tests, fix a but in Address.
Extract "PatternFieldGroup" attributes to separate mixin class.

This should be transparent to all users, but allows their reuse (for instance,
in ControlledVocab strings)
Clean up and simplify StructuredText
Add title and description to observables
Add Structured Text tests
Add proper prefixes to IDs
Change default ID prefix from 'cybox' to 'example'
Add URL instance example
Merge remote-tracking branch 'origin/cybox2.0' into cybox2.0