First weekday

Hi Ruslan, 

Thank you for your work on this widget. I really like his easiness and functional. 
One thing I noted where I trying to setup Monday as first weekday - some months has a wrong day order. 
You can see it here, July 1 disappeared : 
![2014-10-08 18-25-57 ios simulator - iphone 6 - iphone 6 ios 8 0 12a365](https://cloud.githubusercontent.com/assets/5666720/4560828/03eacb14-4ef8-11e4-9c0d-c24fe5b0b100.png)

So this pull request contain fast fix for this, please have a look. 
![2014-10-08 18-27-09 ios simulator - iphone 6 - iphone 6 ios 8 0 12a365](https://cloud.githubusercontent.com/assets/5666720/4560827/03e41c38-4ef8-11e4-85b4-84e575634fd5.png)
 
It should work for any weekday as first day. I test it only for Gregorian, so not sure how it will affect other calendars types. 

Again, thank you