check for existing docker commands before trying to create docker

buildScripts/createDockerImage

@@ -2,6 +2,8 @@
 
 # This bash script creates a docker image from an existing pdf2htmlEX
 
+if [ -x "$(which docker)" ]; then
+
   source buildScripts/versionEnvs
 
   source buildScripts/dockerFunctions
@@ -31,4 +33,7 @@ cd ..
 
   docker build -t stephengaito/pdf2htmlex:test-`date +%Y%m%d-%H.%M.%S` dockerDir
 
+else
+  echo "Docker is not installed... skipping creation of a docker image."
+fi