Upgrade jsoncpp to 1.9.4

Bug: 170642246
Change-Id: Id1fae5a1b6421117f923c616718ee4b3571231e0
diff --git a/.travis_scripts/travis.before_install.osx.sh b/.travis_scripts/travis.before_install.osx.sh
new file mode 100644
index 0000000..5d83c0c
--- /dev/null
+++ b/.travis_scripts/travis.before_install.osx.sh
@@ -0,0 +1 @@
+# NOTHING TO DO HERE