auto install phpstan if not installed by using composer.

static_tests.sh

@@ -1,6 +1,11 @@
 #!/bin/bash
 if [ ! -x vendor/bin/phpstan ]; then
+   if which composer >/dev/null 2>&1; then
+        echo "Running Composer to install phpstan."
         composer require --dev phpstan/phpstan
+   else
+        echo "Please install php composer!"     
+   fi 
 fi
 
 ./vendor/bin/phpstan analyse