Make the blogs list sortable (A-Z, Z-A)

Hi,
I am a GSoC candidate (maxday on IRC), I've tried to implement this feature one year ago but it didn't finished it. 
Now I hope it's ok.
![ios simulator screen shot mar 19 2014 2 01 24 am](https://f.cloud.github.com/assets/864493/2457080/393d2684-af2c-11e3-9586-e0c800e7235e.png)
![ios simulator screen shot mar 19 2014 2 02 07 am](https://f.cloud.github.com/assets/864493/2457081/393df316-af2c-11e3-94cc-1d324a803a1d.png)