Use httpbin instead of jsontest for request tests

jsontest was over quota and returning 5** errors
Use WIP branch of Specta for Xcode 6 beta support

This is gross, but we need to test this against iOS 8 and I don't want to
convert everything to Kiwi.
Add workaround for XCTest not being available to non-test targets

Adds XCTest framework search path to the Specta pod target so that it's able to
build. As of Xcode 6 XCTest is only available to test targets, and Cocoapods
doesn't have a fix for this on master yet.
Extend native Object prototype with EventEmitter properties

This allow the use of direct events to be used instead of only allowing global
events. The change that needed to be made for this to be possible was extending
Object.prototype with EE's properties but making them not enumerable. Doing this
previously with enumerable properties caused marshalling JS Objects to
NSDictionaries to include those enumerable properties (this was found by
investigating the JSValue toDictionary method in the JSC API source in WebKit).
Bump target to 8.0/10.10 and remove NSDate->JS bug workaround

There used to be an issue in 7.0/10.9 converting NSDate seconds to JS milliseconds, but it's
been fixed in subsequent OS releases.
Update new target OS versions in readme
Merge pull request #1 from RobotsAndPencils/ExtendObjectWithEventEmitter

Extend native Object with EventEmitter properties