Allow process timeouts to be specified for Yui

- provide a setTimeout method to specify the timeout that the process can run for (currently hardcoded to 60 seconds)
- provide a means that this can be applied to other filters which use the ProcessBuilder
Merge remote branch 'upstream/master'
Add a simple array cache to a provide a consistent interface for non-persistant caches
Added filter for Dart
Assetic Issue #248

https://github.com/kriswallsmith/assetic/issues/248
fonts_dir as config entry, not command line param
Merge pull request #317 from xzyfer/feature/controller/asset-cache

Add a non-persistant asset cache
Merge pull request #329 from shql/master

Added support for compass fonts_dir config entry
Fixed the tests for the Twig extension
Made the initialization of variable values lazy

This avoids calling the supplier if you don't have any asset using
variables.
It also fixes symfony/AsseticBundle#138 as the supplier is not called
anymore as soon as the Twig globals are read from the extension.
Merge pull request #332 from stof/lazy_value_retrieving

Made the initialization of variable values lazy
added missing test group
Merge pull request #277 from steveybaby2/master

[Filters] Fixed issue with Yui process timing out by providing a setTimeout function
In LessphpFilter, allow formatter to be changed.
In LessphpFilter, allow comments to be preserved in the output.
Add tests for LessphpFilter's 'formatter'.

https://github.com/amyboyd/assetic/commit/180c7dbe3b1a1a78348188682b76cf3d479f5320
Add tests for LessphpFilter's 'preserve comments'.

https://github.com/amyboyd/assetic/commit/3351d6386be3452e7529a3dc477784da8688a3d6
add setter for http_fonts_path
added ProcessFilter::createProcessBuilder()
renamed abstract class per standards