Allow extension keys in Info Object

[mattyr]

per http://swagger.io/specification/#infoObject

[LeFnord]

thanks @mattyr … but

• make rubocop happy → run bundle exec rake to see the failures
• missing changelog entry
• please add a entry to extension section in the README

[mattyr]

made the requested changes -- also made the extension format conform better with existing extensions (x: {foo: 'bar'} rather than "x-foo": 'bar').

quick question re: rubocop: i was getting a ton of errors so i thought that was ignored. looks like 99% are "Missing frozen string literal comment". I disabled that using .rubocop.yml file and just addressed those issues specific to these changes. Would you like a PR that either:

• disables the "Missing frozen string literal comment" test universally, or
• adds the comment to all needed files (not sure if this will introduce new spec failures)

[coveralls]

Coverage increased (+2.4%) to 99.754% when pulling dea6383 on mattyr:allow-extensions-in-info into 79052e3 on ruby-grape:master.

[LeFnord]

@mattyr … its a bit curious that this cop pops up, cause it is running some weeks, but prefer not to mix up your PR with a maintainance PR, and yeah here is it green

[LeFnord]

👍 very cool, thanks

[coveralls]

Coverage increased (+2.3%) to 99.631% when pulling dea6383 on mattyr:allow-extensions-in-info into 79052e3 on ruby-grape:master.