Add simple flush/compact threads to tablet server for demo
Add simple flush/compact threads to tablet server for demo

This is throwaway code, but allows us to demo with on-disk datasets.
Tested manually using the twitter demo.

Change-Id: Ieb27f9f566b6494b25ef338bf18998b7902a6b91
Reviewed-on: http://gerrit.ent.cloudera.com:8080/237
Reviewed-by: David Alves <33ea948168c114d220e0372a903be6ee60f6396e@cloudera.com>
Tested-by: jenkins <c14f3aae4f03a600341a3b92ec1ffaac2338cde0@cloudera.com>

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