Handle bad request exceptions properly (#7)

* Handle bad request exceptions properly

* Fix travis build for ~3.2@dev

Put exception message into the exception container

Some loggers like gelf do not like empty messages

Do not output JsonRpcError data until debug is enabled (#5)

Exception conversion (#4)

* Revert 2.7 dropped testing

* Exception conversion

* Revert 2.7 dropped testing

Initial public release