Implement $eq support for sub document

[maheshrajamani]

Extend $eq operator support for elements of object (sub document) type.
Eg:
Match the documents which has an element for the given field which is of object type whose value match the exactly to the subdocument provided in the filter.
{ "find" : { "filter" : { "field" : { "$eq" : {"a" : "b"}} } } }

This should also work for short cut equals
{ "find" : { "filter" : { "field" : {"a" : "b"} } } }
This will corresponds to CQL where clause as WHERE array_equals['field'] = hash( {"a" : "b"})

[amorton]

@maheshrajamani I just wanted to check - this was a typo: This will corresponds to CQL where clause as WHERE array_equals['field'] = hash( {"a" : "b"}) It should be the subdoc_equals column in the table.

[maheshrajamani]

@amorton Yes it's a typo it should have been WHERE sub_doc_equals['field'] = hash( {"a" : "b"})