adding json lint check

.travis.yml

@@ -4,7 +4,7 @@ python:
   - "2.7"
 install:
   - "pip install --allow-all-external -r requirements.txt"
-  - "sudo apt-get install -y npm"
+  - "sudo apt-get install -y npm python-demjson"
   - "sudo npm install -g js-yaml"
 script:
   - |
@@ -16,6 +16,14 @@ script:
       fi
     done
   - |
+    for json in $(find . -name "*.json"); do
+      jsonlint $json
+      if [[ $? -ne 0 ]]; then
+        echo "ERROR parsing $json"
+        exit 1
+      fi
+    done
+  - |
     plays="aws bastion certs commoncluster common demo devpi discern edx_ansible edxapp elasticsearch forum ora rabbitmq worker xqueue xserver"
     set -e
     cd playbooks/edx-east