Clone DroidBench in the desired place without pushhd/popd

IMHO this is a simpler way to achieve the desired result.

.travis.yml

@@ -3,11 +3,9 @@ jdk: oraclejdk8
 before_install:
  - "export DISPLAY=:99.0"
  - "sh -e /etc/init.d/xvfb start"
- - "pushd /tmp"
- - "git clone --depth=1 https://github.com/secure-software-engineering/DroidBench.git"
- - "popd"
  - "mkdir -p $TRAVIS_BUILD_DIR/com.ibm.wala.dalvik.test/lib"
  - "find /usr/local -name dx.jar -exec cp '{}' $TRAVIS_BUILD_DIR/com.ibm.wala.dalvik.test/lib/dx.jar ';'"
+ - "git clone --depth=1 https://github.com/secure-software-engineering/DroidBench.git /tmp/DroidBench"
 install:
  - mvn clean verify -DskipTests=true -B -q
 script: