add key/value store (redis or similar)

I never really received any useful information, but there are two different things that are not documented:

    * MEMCACHE method in datasources
    * memcache JAR in the LM agent/lib directory

For the latter, I did figure out it is this one by examining the ToC: com.danga.MemCached

I have had more difficulty tracking down official documentation on that than I would expect (though I am sure it is out there).  I have found some useful examples, so will see if I can actually leverage the library.

https://sites.google.com/site/networkprogrammingforjava/home/miscellaneous/others/memcached