Add libleveldb-dev for travis ci (#848)

.travis.yml

@@ -3,11 +3,9 @@ dist: trusty
 language: python
 before_install:
   - sudo add-apt-repository -y ppa:streetcrypto7/rocksdb
+  - sudo add-apt-repository -y ppa:streetcrypto7/leveldb
   - sudo apt-get -qq update
-  - sudo apt-get install -yq libsnappy-dev zlib1g-dev libbz2-dev libgflags-dev liblz4-dev librocksdb-dev
-  - 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
+  - sudo apt-get install -yq libsnappy-dev zlib1g-dev libbz2-dev libgflags-dev liblz4-dev librocksdb-dev libleveldb-dev
 python:
   - "3.6"
   - "3.6-dev"