Remove AbstractSession.objectToKey.

* Instead add a trivial method to Persister to allow fetching the id from an entity.
* Prevents potential problems with entities with overridden equals/hashCode.
Fix incorrect clearing of session attributes for entity.
move location of BeforeValidateHelper,since there is nothing Hibernate specific about it
add some version warnings to the mongo plugin docs
Merge pull request #106 from aeischeid/master

adding note for mongo plugin and grails version compatibility
Fix data corruption problem caused by proxy persistence.

Included test case which fails without fix and passes with it.
Return real entity instead of proxy where available in session.

This matches gorm-hibernate behaviour.
Merge branch '1.x'

Conflicts:
	grails-datastore-gorm-tck/src/main/groovy/grails/gorm/tests/UpdateWithProxyPresentSpec.groovy
Fix issue with round tripping of DBObjects.

Previously, embedded collections were saved and read in an incompatible
way (array vs BasicDBList).
Added test case for round tripping.
Merge branch '1.x'
fix failing tests, remove dependencies on commons-beanutils and commons-lang
remove redundant tests, already tested elsewhere
added stub to avoid including dependency on grails-datastore-gorm-hibernate
fix failing test
increase heap size for running forked tests
test for GRAILS-9882
test for GRAILS-9876
bug fix - wasn't using the value of onlyExtendedMethods
removed grails-hibernate dependencies
restored commented out code