fuel/core — pull request #805 by OscaTutenchamon (2012-01-31 10:11:59+00:00)
Title: Fuel constants should be saved as constants not string values in config files

I noticed that while saving configs, constants such as APPPATH are being exported to strings and written in that form in php files.
```
'cache_dir' => 'var/www/fuel/app/cache/',
```
Now, every constant found at the beginning of the string is replaced by its name:
```
'cache_dir' => APPPATH.'cache/',
```