Use `STAssertEqualObjects` instead of `STAssertTrue`

Use of `STAssertEqualObjects` for asserting equivalence of objects instead of `STAssertTrue` will show us more useful information if tests are fail.

Here is an example of failed test message with `STAssertTrue`:

![2013-05-18_1857](https://f.cloud.github.com/assets/217368/521771/30ee8786-bfd4-11e2-8600-21b5a58a8886.png)

And here is the same with `STAssertEqualObjects`:

![2013-05-18_1856](https://f.cloud.github.com/assets/217368/521769/285b98d4-bfd4-11e2-81ff-0d11ecf72872.png)