Remove Bean.clone()

Clashes with generic union types
Immutable beans no longer generate a clone method
Use JodaBeanUtils.clone(bean) instead
Fixes #66
Add getter/setter style of "field"

Enables weird getter/setter
Fixes #67
Generate Javadoc param tags for generic types in meta/builder

Fixes #68
Add @ImmutableValidator

Allow immutable constructors to be manually validated
Fixes #65
Fixes from static analysis