ENH: Option to prefix dns name of clusters with the tag name.  ie master on mycluster --> mycluster-master.

Hi,  

This PR is a collection of a couple different improvements.  The PR is backwards compatible and contains:
  - 1st commit: optparse and config option to prefix host names.
  - 2nd commit: optparse option in removenode and addnode to use a specific template (so plugin on_shutdown runs properly)
      - optparse option -f to force shutdown on removenode even if sge and other plugins fail   

The first commit adds the option to prefix dns hostnames with the cluster tag.  I wrote about this a little while ago on the mailing list and finally had some time today to do this.   http://star.mit.edu/cluster/mlarchives/1820.html

    Specifically, if you have a cluster named "mycluster" and set the option the prefix dns names with the cluster tag, the new naming scheme would be:
       master --> mycluster-master
       node001 --> mycluster-node001 

The second commit adds the options to use a template defined in your starcluster config on addnode and removenode, so that the appropriate cluster settings are used when you add/remove nodes from the cluster

    starcluster addnode -c myconfig ...
   
The second commit also adds a --force option to removenode that terminates the node whether or not the plugins close successfully


Please take a look and let me know what you think!  I also started 0.95 in the Changelog.

Alex