Adding "UNWRAP_SINGLE_VALUE_ARRAYS" DeserializationFeature

Fixes issue #381. Added new feature that determines whether it is
acceptable to coerce a single value array (in JSON) to the corresponding
value type.
Fix for UNWRAP_SINGLE_VALUE_ARRAYS for bean deserialization

Added fix to BeanDeserializerBase that when deserializing a bean, if the
UNWRAP_SINGLE_VALUE_ARRAYS feature is enabled, to unwrap a single
element array automatically.
Added test cases for single value arrays bean deserialization

Added test cases for single value arrays bean deserialization
Adding additional test cases for Issue # 381
Merge pull request #384 from yinzara/master

Added new UNWRAP_SINGLE_VALUE_ARRAYS DeserializationFeature