Fix rollup repair
stop rolling up slots for which shard ownership has changed
Merge pull request #260 from lakshmi-kannan/bf_fix_rollup_repair

Fix rollup repair
continue if null slotKey
Merge pull request #261 from fourk/dont_roll_data_without_shard

Stop rolling up slots for which shard ownership has changed
Update README.md

add presentation link
Add idea about exploring Dropwizard.