Adding @since 2.4 and removing unused null check
Adding Character tests

Adding Character tests to prove there 'null' JSON check in
NumberDeserializer removed in commit
72e590f80883551fe212bfdabf65993eaf66fa1e was not required
Merging from upstream
Merge pull request #387 from yinzara/master

Requested changes for new UNWRAP_SINGLE_VALUE_ARRAYS DeserializationFeature