With Less 1.4 "Maths is required to be in parenthesis"

see changelog at http://lesscss.org/
Allow user to add option when using the LessFilter
LessFilter: Add setLoadPaths method
ScssFilter: Add setLoadPaths method
LessphpFilterTest can't inherit LessFilterTest because we didn't use the same options
Allow user to add Parser option such as "relativeUrls"
Merge pull request #402 from BenoitLeveque/fix-less-1.4-strict-math

With Less 1.4 "Maths is required to be in parenthesis"
We can't use parserOptions attributes because each assets alter this var
initial framework for asset dependencies
added AssetInterface::getSourceContent()
added CssUtils
moved patterns to constants
added CssUtils::extractImports()
initial pass at making SassFilter dependency aware
refactored CacheBustingWorker to use deep mime
made some members protected
minor test fixes
cleaned up use statements
fixed typo
cs fixes