Fix async handling of multiple files

The pull request i created yesterday introduced a bug when handling multiple async template compilations in a single target using the grunt file blob syntax.

This made the task finish with `async(done);` after the first template was compiled instead of waiting for all compilations, which could lead to unwanted consequences.

To be able to easier handle this asynchronous parts, i added `es6-promise` as a dependency and fixed the bug. I also changed the version number to 0.0.6 in package.json.

Please accept pull request and republish to npm to bump version number and sorry for the inconveniences.