Improve Travis stability

Signed-off-by: Vadim Markovtsev <vadim@sourced.tech>

.travis.yml

@@ -48,7 +48,9 @@ before_install:
   - pip3 --version
   - pip3 install --user --no-build-isolation -r requirements.txt tensorflow
   - docker run -d --privileged -p 9432:9432 --name bblfshd bblfsh/bblfshd
-  - docker exec -it bblfshd bblfshctl driver install --all
+  - docker exec -it bblfshd bblfshctl driver install python bblfsh/python-driver:latest
+  - docker exec -it bblfshd bblfshctl driver install go bblfsh/go-driver:latest
+  - docker exec -it bblfshd bblfshctl driver install java bblfsh/java-driver:latest
   - curl -L "https://storage.googleapis.com/tensorflow/libtensorflow/libtensorflow-cpu-$(go env GOOS)-x86_64-$TENSORFLOW_VERSION.tar.gz" | sudo tar -C /usr/local -xz
   - sudo ldconfig
 install: