Move hudson.model.Jenkins to be jenkins.model.Jenkins - part II

Just import changes, from hudson.model.Jenkins -> jenkins.model.Jenkins,
and Javadoc comments.

Signed-off-by: Nigel Magnay <nigel.magnay@gmail.com>

core/src/main/java/hudson/PluginStrategy.java

@@ -23,7 +23,7 @@
  */
 package hudson;
 
-import hudson.model.Jenkins;
+import jenkins.model.Jenkins;
 
 import java.io.File;
 import java.io.IOException;