Cardano Updates

add ping() to sqlite connection

impl Sync for BlockStore

remove internal sqlite connection pool

remove internal sqlite connection pool

remove internal sqlite connection pool

remove internal sqlite connection pool

remove unnecessary mutability from connect()

make use of sqlite transactions

this should help to eliminate more application-level locks in database wrappers

make use of sqlite transactions

this should help to eliminate more application-level locks in database wrappers

use tempfile and criterion only for bench builds

allow cloning the sqlite pool in new impl (#232)

allow cloning the sqlite pool in new impl

Merge pull request #242 from input-output-hk/network-grpc-default-executor-too

rename the new function to with_executor and implement new new with default executor

use new constructors in storage benchmarks

Merge pull request #237 from input-output-hk/safer-sqlite-block-store

constructors for sqlite in file and in memory