Implemented JSON payload binder.

XML would probably be a piece of cake…
37 new lines of panicking code
Passing test
Validate calls a method “Validate<StructName>” to perform validation
Started pipeline; code doesn’t compile
Changed the validation package to use an interface instead of reflection
First passing tests of new `binding` package
Major refactoring of errors; lots of fixes; more tests; tests pass.
A request without form data won’t error; when we have to guess, guess JSON first.
Demystifying the “required” attribute…
Major usability fixes; could use some optimizing now probably
Deleted form package; new binding package ready for review
Form deserializer now handles bool, string, int types, and float types (related to #32)
Godoc; new standalone ErrorHandler middleware.
Added readme documentation.
Merge branch 'master' of github.com:smartystreets/martini-contrib into smartystreets-master

Conflicts:
	form/form.go
Removing form package
Fixed up some docs and typo