Openwebapp support

	modified:   templates/index.html.ep
	modified:   templates/layouts/default.html.ep
	new file:   templates/manifest.webapp.ep
Add icon 128px for openwebapp (firefox os)
Add accept="image/*" in the form for accept only images
Add JS for install openwebapp and share image to lutim app
Add manifest for openwebapp


TODO : add HEADER "Content-Type : application/x-web-app-manifest+json" on manifest.webapp