[#1048] allow flash messages to time out
[#1048] allow flash messages to time out

webflash messages now time out after 45s.  JS flash() messages
now support setting a timeout.  Save messages don't need to time out
because they go away as the page is changing.

heiths/allura,Bitergia/allura,heiths/allura,apache/allura,heiths/allura,lym/allura-git,apache/incubator-allura,leotrubach/sourceforge-allura,heiths/allura,apache/incubator-allura,apache/allura,leotrubach/sourceforge-allura,Bitergia/allura,apache/allura,apache/incubator-allura,leotrubach/sourceforge-allura,leotrubach/sourceforge-allura,apache/allura,lym/allura-git,lym/allura-git,Bitergia/allura,Bitergia/allura,lym/allura-git,apache/incubator-allura,apache/allura,lym/allura-git,heiths/allura,Bitergia/allura