Implement helpers to convert JField names from underscore/camelcase
Camel case in the front, underscore in the back.

We now convert all JSON fields in incoming JSON to camel-cased field
names before they hit the deserialization chain. On the outbound side,
we convert all camel cased JSON field names to underscored.

WePay's API uses underscored fieldnames. While Ruby engineers love
underscores, Scala engineers, like myself, absolutely do not. This
commit will break deserialization of all resources until they are fixed.
Camel case params for WePayError.
Camel case param for WePayToken.
Improved error behavior.

Now, if we can't deserialize a WePayError for some reason, we'll include
the entire response body in the ParamFailure as a String.
Fix field name underscoring.

We were applying *that* at the incorrect point...
Get Account resource compiling and passing specs.
Get App endpoint working.
Get Withdrawal resource working.
Get Preapproval resource working.
Get user resource working.
Get Checkout working.
Get CreditCard working.
Remove println from a test.