Tests/it specs objc

Added it tests in Objective-C as discussed in #200. All comments and feedback are warmly welcomed :+1: 

The tests are written based on their Swift counterparts. Except that IDETestManager didn't like having empty string as a test name (or description of it statement in this case). It made Xcode crash. I got the error message (see below) captured when running tests via Rake. Due to this I changed the empty string test to testing string containing only whitespace. Though I'm not totally sure if it's meaningful (and if it is, should it be also added to swift test).

```
2014-12-10 19:05:21.205 xcodebuild[71530:5249343]  DVTAssertions: ASSERTION FAILURE in /SourceCache/IDEFrameworks/IDEFrameworks-6604/IDEFoundation/Testing/IDETestManager.m:1440
Details:  testName should be a non-empty string, but it's an empty string
Object:   <IDETestManager: 0x7fc81de293f0>
Method:   -_writeTestResultsBundleForTestRunners:successCount:failureCount:
Thread:   <NSThread: 0x7fc81ef36630>{number = 9, name = (null)}
Hints: None
Backtrace:
  0  0x0000000106c182ca -[DVTAssertionHandler handleFailureInMethod:object:fileName:lineNumber:assertionSignature:messageFormat:arguments:] (in DVTFoundation)
  1  0x0000000106c17d1f _DVTAssertionHandler (in DVTFoundation)
  2  0x0000000106c1800e _DVTAssertionFailureHandler (in DVTFoundation)
  3  0x0000000107358411 -[IDETestManager _writeTestResultsBundleForTestRunners:successCount:failureCount:] (in IDEFoundation)
  4  0x000000010735beba __245-[IDETestManager testOperationForTestingSpecification:executionEnvironment:withBuildOperation:buildParameters:runDestination:workspace:actionRecord:schemeIdentifier:outSchemeActionResultOperation:error:launchParametersBlock:actionCallbackBlock:]_block_invoke1077 (in IDEFoundation)
  5  0x0000000106a9439f -[DVTOperation main] (in DVTFoundation)
  6  0x00007fff8fb4959c -[__NSOperationInternal _start:] (in Foundation)
  7  0x00007fff8fb491a3 __NSOQSchedule_f (in Foundation)
  8  0x00007fff934f9c13 _dispatch_client_callout (in libdispatch.dylib)
  9  0x00007fff934fd365 _dispatch_queue_drain (in libdispatch.dylib)
 10  0x00007fff934feecc _dispatch_queue_invoke (in libdispatch.dylib)
 11  0x00007fff934fc6b7 _dispatch_root_queue_drain (in libdispatch.dylib)
 12  0x00007fff9350afe4 _dispatch_worker_thread3 (in libdispatch.dylib)
 13  0x00007fff8bb9b6cb _pthread_wqthread (in libsystem_pthread.dylib)
 14  0x00007fff8bb994a1 start_wqthread (in libsystem_pthread.dylib)
rake aborted!
RAKE TASK FAILED: xcodebuild -workspace Quick.xcworkspace -scheme Quick-iOS clean test
/Users/markus/github/Quick/Rakefile:2:in `run'
/Users/markus/github/Quick/Rakefile:8:in `block (2 levels) in <top (required)>'
Tasks: TOP => test:ios
(See full trace by running task with --trace)
```