Fixes unit test on recursiveModuleCompile

This removes previous assertion and adds a new test to check for current working directory being the same after recursive compiling.
I ran `npm test` from `/path/to/traceur-compiler` and I get that `cwd === /path/to/traceur-compiler/test`. At the same time `outputDir === /path/to/traceur-compiler` in `recursiveModuleCompileToSingleFile`, meaning that without https://github.com/mciparelli/traceur-compiler/commit/4ccff4f0abc1ca2bbac1b41704388be64e141fb2 the same test won't pass.