fix(Grunt): update grunt-wiredep to ^1.9.0

See http://stackoverflow.com/a/25713634/2578205
and http://stackoverflow.com/a/25715527/2578205

Error shown on `grunt serve`:
Running "wiredep:app" (wiredep) task Warning: ENOENT, no such file or
directory '/usr/share/nginx/html/data/gaia-app/app/bower.json' Use
--force to continue.
Merge branch 'drag-n-drop' of github.com:mozilla/seasponge into drag-n-drop