Move sql store implementation into its own package

SQL is one implementation of EventStore but there could be others. Move
all sql related classes into their own package to unclutter the base
package.

Change-Id: Ie2a01ba5cd40a7ab1290c276ce17bc4cf00be372
15 files changed
tree: 8e59455f5c13fd0e839de31e9911ec41658057f0
  1. lib/
  2. src/
  3. .buckconfig
  4. .gitignore
  5. BUCK