Added retry for sql statement execution failure

[kaisecheng]

jdbc-integration 5.4.1 has changed the way of using the connection pool. Since then, the sql statement execution does not retry for any failure.

This PR adds a retry loop using the new settings statement_retry_attempts and statement_retry_attempts_wait_time to retry the failed statement execution.

Setting	Default Value	Comment
statement_retry_attempts	1	Maximum number of times to try running the statement
statement_retry_attempts_wait_time	0.5	Number of seconds to sleep between statement execution

Fix: #124

[andsel]

LGTM

tried shutting down and tearing up a local DB between the statement_retry_attempts_wait_time and worked as expected. Good work.

Maybe a nitpick, instead of statement_retry_attempts_wait_time would be better statement_retry_attempts_interval. I think that amongst the plugin's code base the interval suffix is more frequently used than wait_time.
But feel free to skip the suggestion :-)

[kaisecheng]

instead of statement_retry_attempts_wait_time would be better statement_retry_attempts_interval

Thanks for the review and suggestion. There is a connection_retry_attempts_wait_time in existing jdbc config, so I keep it the same naming convention.