don't report connect issues on idle socket
expose jackpot retry options. also splits connection allocation `retries` option
from server retries option.  server retries option is called `failures` as in
the number of failures to allow on the server before marking it as dead.
Merge pull request #128 from ianshward/report-connection-issues

don't report connect issues on idle socket
Merge pull request #127 from ianshward/jackpot-options

expose jackpot retry options.