added NgMinPreProcessor
updated DefaultProcessorProvider with ngmin
Merge pull request #161 from janeklb/feature-ngmin

added NgMinPreProcessor
Merge branch '1.7.x' into issue812
Prepare new development iteration
remove duplicate dependency
get latest changes of NgMinProcessor
rename processor & add more test cases
update logging level for tests to DEBUG
Merge branch 'issue812' into 1.7.x