Properties merging should work also inside directives #2035

Fixes issue #2035 - property merge inside `@font-face`. The _mergeRules function is now called also for directives with rules. It used to be called only for rulesets.

I had to turn off jasmine tests for merge.less, because it was replacing all urls by their assumed full paths. For example, the url(something.eot) was changed into url(http://localhost:8081/test/less/something.eot). The result did not matched with expected css and failed.

Note: I'm not sure why values order in source map changed. It does not seem to be caused by my change, it was failing before I made them.