Bug 820206 - Validate "Webapps:*" message parameters in the parent process (part 2, call .uninstall() from mozIDOMApplicationMgmt in Gaia). r=sicking, a=blocking-basecamp

Bug 820206 - Validate "Webapps:*" message parameters in the parent process (part 2, call .uninstall() from mozIDOMApplicationMgmt in Gaia). r=sicking, a=blocking-basecamp