copy kv encoding test to tornado tests to expose error
copy kv encoding test to tornado tests to expose error

copy
`tests/test_std.py:TestConsul.test_kv_encoding`
test to
`tests/test_tornado.py:TestConsul.test_kv_encoding`
expose error from tornado backend
`ValueError: Body must not be None for method PUT (unless allow_nonstandard_methods is true)`

cablehead/python-consul