Update to snapshot

.travis.yml

 language: java
 script:
-  - set -e
-  - export CROMWELL_VERSION=34
-  - wget https://github.com/broadinstitute/cromwell/releases/download/$CROMWELL_VERSION/womtool-$CROMWELL_VERSION.jar
-  - for F in $(git ls-files *.wdl); do echo $F; java -jar womtool-$CROMWELL_VERSION.jar validate $F; done
+- set -e
+- export CROMWELL_VERSION=34
+#  - wget https://github.com/broadinstitute/cromwell/releases/download/$CROMWELL_VERSION/womtool-$CROMWELL_VERSION.jar
+- wget https://barmsijs.lumc.nl/womtool-35-a7ae2d8-SNAP.jar
+- for F in *.wdl; do echo $F; java -jar womtool-*.jar validate $F; done
+- 'if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then git submodule foreach --recursive git checkout $TRAVIS_BRANCH && git submodule foreach --recursive git pull; fi'
+- "git diff --exit-code || (echo ERROR: Git changes detected. Please update submodules && exit 1)"