Gruntfile.js: replace uglify with copy
Gruntfile.js: replace uglify with copy

uglify was slow so replaced it with
copy temporarily.

Signed-off-by: Kanagaraj M <a744b691cd98174fb19a473a8cf78b810491e452@redhat.com>

kmkanagaraj/usm-client,kmkanagaraj/usm-client