Added InferTypesFromValues flag to XML and JSON TP

XML and JSON TPs are trying to infer the types from the
input data. In some cases this is not desired. Added flag
to allow developers to turn off type inference. By default
the TPs are inferring like before in order to stay
backwards compatible.
Merge pull request #658 from mrange/mrange/json_xml_noinference

Added NoTypeInference flag to Json and Xml TP