Fix extra quotes for de-serialization of _id's stored as Strings.
This is needed so that Jongo domain models can be used
with REST/ any other layer that requires Jackson.
Add additional check for TextNode for converting to
textValue
Simplified implementation based on review comments by: Benoit
Merge pull request #213 from sukrit007/patch_id-string-deserialization

Fix extra quotes for de-serialization of _id's stored as Strings.