Added fish-shell 2.x supports.

I have porting  `bashrc` to `phpbrew.fish`  for fish-shell compatibility and completions supports.

**Install**
Add `. ~/.phpbrew/phpbrew.fish` to your `~./config/fish/config.fish`


**completions demo**

* Commands and Options completion
![general](https://www.dropbox.com/s/4i1oysil7l30ba7/%E8%9E%A2%E5%B9%95%E6%88%AA%E5%9C%96%202014-12-01%2021.31.00.png?raw=1)

* Install Command completion (list available php versions)
![install](https://www.dropbox.com/s/oh49zb0hdmuioug/%E8%9E%A2%E5%B9%95%E6%88%AA%E5%9C%96%202014-12-01%2022.16.21.png?raw=1)

* use /switch command ( list installed php versions)
![use](https://www.dropbox.com/s/s9kb1cq8mv06dgf/%E8%9E%A2%E5%B9%95%E6%88%AA%E5%9C%96%202014-12-01%2022.21.13.png?raw=1)


Also, fixes #286