Personal snipepts support added

My first step to implement a good feature:

* Added new page for snippets managment
* Added new type of snippets. Personal snippets
* Added Public/Private snippets support (All projects snippets will be private)

Looks like this:

![Screenshot 2013-03-25 02 14 54](https://f.cloud.github.com/assets/672631/296035/321b58d8-94d1-11e2-8309-fed187f920c7.png)
![ 2013-03-25 2 16 18](https://f.cloud.github.com/assets/672631/296036/321c89ec-94d1-11e2-90f0-c0e45ca591e9.png)
![ 2013-03-25 2 20 06](https://f.cloud.github.com/assets/672631/296038/544b232a-94d1-11e2-8346-f329870cc937.png)

Plans:
- Search 
- Add versions support