Added check to string validations to skip non-strings
Added check to string validations to skip non-strings

Fixes bug #1249088

Change-Id: Iec0e38d5f1d880a11f700b3c7bf8e142caf80670

esikachev/scenario,tellesnobrega/storm_plugin,tellesnobrega/storm_plugin,openstack/sahara,zhujzhuo/Sahara,citrix-openstack-build/sahara,esikachev/scenario,esikachev/sahara-backup,matips/iosr-2015,xme1226/sahara,bigfootproject/sahara,redhat-openstack/sahara,xme1226/sahara,esikachev/scenario,citrix-openstack-build/sahara,egafford/sahara,zhangjunli177/sahara,matips/iosr-2015,matips/iosr-2015,redhat-openstack/sahara,zhangjunli177/sahara,henaras/sahara,tellesnobrega/sahara,mapr/sahara,ekasitk/sahara,keedio/sahara,egafford/sahara,zhujzhuo/Sahara,mapr/sahara,zhujzhuo/Sahara,zhangjunli177/sahara,crobby/sahara,esikachev/sahara-backup,mapr/sahara,crobby/sahara,openstack/sahara,ekasitk/sahara,bigfootproject/sahara,tellesnobrega/sahara,xme1226/sahara,bigfootproject/sahara,redhat-openstack/sahara,henaras/sahara,henaras/sahara,keedio/sahara,citrix-openstack-build/sahara,crobby/sahara,tellesnobrega/storm_plugin,esikachev/sahara-backup,ekasitk/sahara,keedio/sahara