DATAREST-221 - Improvements in ProxyProjectionFactory.

PropertyAccessingMethodInterceptor now ignores Object methods and forwards them to the proxy target. ProxyProjectionFactory now correctly sets up the SpEL root object for reference in expression on accessors.
DATAREST-150 - Added test case showing PUT now works correctly.

The JIRA issue asserts that PUT wasn't properly storing things. But now it does. A partial record causes all other fields to get nulled out. Added a test case to confirm this.

Original pull request: #134.