Use `XCTAssertEqual` instead of `XCTAssertTrue`

So if a test fails `XCTAssertEqual` gives more information and in a nicer way.

## XCTAssertTrue

![2014-10-05_2253](https://cloud.githubusercontent.com/assets/217368/4519832/00fe0ede-4ccd-11e4-8c62-3975082ea001.png)

## XCTAssertEqual

![2014-10-05_22542](https://cloud.githubusercontent.com/assets/217368/4519836/17c6bfe4-4ccd-11e4-84bc-4c25ae5b66bc.png)