Add escaped quote ('\"') character.

Syntax highlighting breaks when using `'\"'` for character comparisons.

![vim-syntax-small](https://cloud.githubusercontent.com/assets/916295/3469379/dcf4a278-02ad-11e4-9649-ae2bf4dcc0bb.png)
This commit solves the problem. 

Moreover, syntax highlighting is different for case, `'\''`, but I am not sure how to approach to that. Adding `'` to `scalaEscapedChar` does not solve, since in that case syntax is highlighted only for `'\'`.