librocksdb is unauthenticated

.travis.yml

@@ -4,7 +4,8 @@ language: python
 before_install:
   - sudo add-apt-repository -y ppa:giskou/librocksdb
   - sudo apt-get -qq update
-  - sudo apt-get install -yq librocksdb libsnappy-dev zlib1g-dev libbz2-dev libgflags-dev
+  - sudo apt-get install -yq libsnappy-dev zlib1g-dev libbz2-dev libgflags-dev
+  - sudo apt-get install -yq --allow-unauthenticated librocksdb 
   - wget https://launchpad.net/ubuntu/+archive/primary/+files/leveldb_1.20.orig.tar.gz
   - tar -xzvf leveldb_1.20.orig.tar.gz
   - pushd leveldb-1.20 && make && sudo mv out-shared/libleveldb.* /usr/local/lib && sudo cp -R include/leveldb /usr/local/include && sudo ldconfig && popd