Validate json variable in sanity check
Validate json variable in sanity check

Some variables could be specified as JSON format. However, once the
variables had invalid json format, playbook produces an error which
is very complicated - e.g bz#1515746.

This patch adds json format varidation in sanity check to solve it.

bparees/openshift-ansible,jwhonce/openshift-ansible,sdodson/openshift-ansible,markllama/openshift-ansible,jwhonce/openshift-ansible,rhdedgar/openshift-ansible,liggitt/openshift-ansible,rjhowe/openshift-ansible,aveshagarwal/openshift-ansible,jwhonce/openshift-ansible,miminar/openshift-ansible,rjhowe/openshift-ansible,aveshagarwal/openshift-ansible,gburges/openshift-ansible,maxamillion/openshift-ansible,markllama/openshift-ansible,mwoodson/openshift-ansible,tagliateller/openshift-ansible,miminar/openshift-ansible,maxamillion/openshift-ansible,aveshagarwal/openshift-ansible,kwoodson/openshift-ansible,nak3/openshift-ansible,sdodson/openshift-ansible,gburges/openshift-ansible,maxamillion/openshift-ansible,sdodson/openshift-ansible,maxamillion/openshift-ansible,kwoodson/openshift-ansible,ewolinetz/openshift-ansible,ewolinetz/openshift-ansible,miminar/openshift-ansible,miminar/openshift-ansible,rjhowe/openshift-ansible,liggitt/openshift-ansible,tagliateller/openshift-ansible,liggitt/openshift-ansible,markllama/openshift-ansible,ewolinetz/openshift-ansible,akram/openshift-ansible,akram/openshift-ansible,maxamillion/openshift-ansible,rjhowe/openshift-ansible,aveshagarwal/openshift-ansible,sdodson/openshift-ansible,jwhonce/openshift-ansible,bparees/openshift-ansible,nak3/openshift-ansible,ewolinetz/openshift-ansible,mwoodson/openshift-ansible,jwhonce/openshift-ansible,openshift/openshift-ansible,tagliateller/openshift-ansible,ewolinetz/openshift-ansible,tagliateller/openshift-ansible,openshift/openshift-ansible,markllama/openshift-ansible,rhdedgar/openshift-ansible,markllama/openshift-ansible,sdodson/openshift-ansible,liggitt/openshift-ansible,miminar/openshift-ansible,liggitt/openshift-ansible,aveshagarwal/openshift-ansible,tagliateller/openshift-ansible,rjhowe/openshift-ansible