* Update Block w/ newest Block
* Add cascading delete to blocks and transactions tables
* Add handling for new conflicting blocks
* Command line version of sliding window n behind HEAD
* The command populates up to the highest known block number
* The anticipated use case is that the listener will be running
in parallel to the populateBlocks command
* This will mean that the listener is responsible for picking up
new blocks, and the populateBlocks command is reposible for
historical blocks
* Reformat SQL statements
