update readme to use requirements.txt instead of requirements-dev.txt
update readme to use requirements.txt instead of requirements-dev.txt

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