Add gabriela font as fallback for cyrilic

Because I use cyrillic and like litewrite a lot :)
Before:
![screenshot - 11202013 - 11 34 51 pm](https://f.cloud.github.com/assets/128981/1586627/9cfc03ce-522b-11e3-8053-92eadb75b6db.png)
After:
![screenshot - 11202013 - 11 35 02 pm](https://f.cloud.github.com/assets/128981/1586626/9cac42f8-522b-11e3-9be7-e1ef05cb12b0.png)
Font is free: http://www.fontspace.com/eduardo-tunni/gabriela

*It would be nice if you switch to this font, but I let this for core devs to decide.*