Add Puppet-Version: !X skip to apply tests

Setting Puppet-Version: !X (where X would usually be 3) marks a hosts
as not wanting to run the apply tests for that puppet version.  This
is helpful for puppet4 hosts that wish to bring in new modules that
are not puppet3 compatible.

Change-Id: I081d15a53bd85152e7729c4c1da094dfee6d7073

tools/apply-test.sh

@@ -49,8 +49,13 @@ fi
 FOUND=0
 for f in `find applytest -name 'puppetapplytest*' -print` ; do
     if grep -q "Node-OS: $CODENAME" $f; then
-        cat applytest/head $f > $f.final
-        FOUND=1
+        if grep -q "Puppet-Version: !${PUPPET_VERSION}" $f; then
+            echo "Skipping $f due to unsupported puppet version"
+            continue
+        else
+            cat applytest/head $f > $f.final
+            FOUND=1
+        fi
     fi
 done