Removed provider@user/repo support. Added '_' to allow character for url regex.

Signed-off-by: Rack Lin <racklin@gmail.com>
remove wrong description in comments.

Signed-off-by: Rack Lin <racklin@gmail.com>
Merge pull request #409 from racklin/issue/simple_dsl

Removed provider@user/repo support.
Fixes extension list / enable /disable not working when extension source not in root directory.

Signed-off-by: Rack Lin <racklin@gmail.com>
rewrite configM4Exists and lookupDirectories at caller side.

Signed-off-by: Rack Lin <racklin@gmail.com>