v1.10.2-statediff-0.0.19

This is an internal release to enable us to work with the statediffing service (v0.0.19). This release is rebased on top of master branch go-etheruem v1.10.2

• Improve error logging
• Fix Postgres connection leak
• Updated docs
• Include Postgres migrations
• Includes the fix for #57, whereby state and storage leaf keys are now recorded in the records that indicate when a leaf node is pruned away from the trie.