Use NSCalendarUnitWeekOfYear
Set indent size on project's level

So Xcode will ignore my global setting of indenatation level (2) and
will use the value specified in the project file.
Upgrade project file to recommended settings
Remove `levenshteinDistanceWithString...`

Looks like it was causing crashes like this;
> xctest(8240,0x7fff77890310) malloc: *** error for object 0x100823c08:
> incorrect checksum for freed object - object was probably modified
> after being freed.
> *** set a breakpoint in malloc_error_break to debug

I didn't get what actually was wrong there so as possible solution I'm
proposing to remove it. Probably it was added because on different OS
(OS X and iOS) date formatter may return different values. But right now
the project configured that way that it runs tests only in OS X. And I
expect it returns the same values all the time.

Fixes #34
Use `XCTAssertEqual` instead of `XCTAssertTrue`

So if a test fails `XCTAssertEqual` gives more information and in a
nicer way.
Merge pull request #42 from yas375/use-xcassertequal

Use `XCTAssertEqual` instead of `XCTAssertTrue`
Merge pull request #43 from yas375/fix-unit-tests

Ok, since we are changing the deployment target to be something much more recent, like iOS 7 (and possibly OSX 10.9) I think we don't need to worry about formatting differences between OS X/iOS versions. Here's to hoping not anyway.
Merge pull request #41 from yas375/fix-weeksSinceDate-and-weeksUntilDate

Use NSCalendarUnitWeekOfYear
specifying deployment target 7.0/10.8