copied draft3 code into draft4 namespace
we index from 0 here, folks
updated schema test suite
describe the update task
fixed draft4 changes to optional/format
draft4 passes min and maxProperties
draft4 passes tests for 'required'
ignore the 'dependencies' test until we have working remotes
draft4 passes multipleOf tests
passing tests for 'not', surprisingly enough
tests passing for allOf; fix to required
tests passing for anyOf
tests passing for oneOf
update Testify dep
converging the basic validator classes
extracted and abstracted common code from drafts
updated readme for draft 4.

may contain some errors. definitely incomplete; iirc we moved draft 4 support to
the 0.2.0 milestone, for example, and I think the benchmarks are also expanded.
updated official test suite from upstream
#42 ignoring the unicode surrogate pairs in tests
use CS 1.7