Add context to error messages
Do not count patternProperties as additionalProperties when
additionalProperties is false.  Added test that is pending in
JSON-Schema-Test-Suite.
( https://github.com/json-schema/JSON-Schema-Test-Suite/pull/45 )

Refactored patternProperties validation into
validatePatternProperties().  Unlike other validate* methods, this one
returns a boolean as to whether any of the patterns matched so we know
whether we can override additionalProperties.
Merge remote-tracking branch 'tolsen/patternProperties-are-not-additionalProperties'

Conflicts:
	validation.go