bump gulp plugin version and update file format.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
add gulp-plumber package.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
update readme.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Merge pull request #45 from appleboy/patch

Prevent pipe breaking caused by errors from gulp plugins