installation: richer uninstall-jquery-plugins

• Amends make uninstall-jquery-plugins statements, for some files and folders were not deleted during uninstall-jquery-plugins, even though they were added by install-jquery-plugins. (PR #2418)

Signed-off-by: Avraam Tsantekidis <avraam.tsantekidis@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>