Pass options from callers directly to gulp-compass after merging with defaults.

Index.js line 23 merges the user supplied defaults with some internal defaults. But when calling 'gulp-compass' on line 33, it explicitly passes on certain fields, effectively dropping everything else from the caller supplied options array.

This is a problem if the user pulls in some scss files from another source (ex: bootstrap via bower) and needs to specify "import_path" for gulp-compass to pass on to compass.