Add instructions on using compressed InnoDB tables

Add some instructions on using InnoDB table compression along with
benchmarks for optimal KEY_BLOCK_SIZE for each table.

Using binary storage and default settings for firstbits and scriptsigs,
a compression ratio of over 50% has been observed by compressing the
largest tables using the appropriate key block sizes.
Merge pull request #27 from dermoth/master

Add instructions on using compressed InnoDB tables
Merge branch 'master' of github.com:jtobey/bitcoin-abe into master-test