Delegate clean in root Makefile.

Change-Id: I3a42695c788164abd0aef0e661b67d95f8cc9925
Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
Implement Makefile for Firefox extension.

Change-Id: Iae167a008b12605a894999564d3546c8c0b5b7d8
Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>