run valgrind in Travis CI for linux only

Author: cdunn2001

.travis.yml

@@ -6,6 +6,8 @@
 #before_install: sudo apt-get install -y cmake
 # cmake is pre-installed in Travis for both linux and osx
 
+before_install:
+  - sudo apt-get install -qq valgrind
 os:
   - linux
   - osx

travis.sh

@@ -25,4 +25,5 @@ make
 if [ "$TRAVIS_OS_NAME" != "osx" ]
 then
   make jsoncpp_check
+  valgrind --error-exitcode=42 --leak-check=full ./src/test_lib_json/jsoncpp_test
 fi