reformat with goimports
add test: JSON requests call the JSON deserializer

Add a simple test to verify that the JSON binder function is called when
the Content-Type is JSON.
do not export DefaultJsonBinder

change DefaultJsonBinder to an unexported function.
refactor request binders

Refactor the JSON request binder so it doesn't change the API or
introduce new exported variables, especially since the previous
implementation didn't make it clear that the Json variable was intended
for internal use only in order to facilitate testing. This change also
makes it so the documentation doesn't have to change.

Make the RequestBinder unexported (RequestBinder -> requestBinder) since it's not
intended to be used by API clients.

Create requestBinders for form-urlencoded and multipart/form-data.
add test for form-urlencoded forms
add tests for multipart/form-data
Errors implement error interface
Merge pull request #13 from doloopwhile/errors

Errors implement error interface
errors.go: Spelling & godoc improvements
update README with newly supported types
Add fieldName as first parameter to Bind and Binder.

Henceforth, types can be re-used without the need to modify them every time
their field name changes. Enables types to be used more than once in a single
form.

closes #3
Improve comments.
Merge pull request #14 from bhcleek/master

update README with newly supported types
Merge pull request #10 from bhcleek/test-json-binding

Test json binding
Merge pull request #15 from bhcleek/binder-with-fieldname

Add fieldName as first parameter to Bind and Binder.