#38 Database connection problems cause htminer_oltp to hang

[Gabriele Bartolini]

Output of "htminer_oltp -vi"

> Discarded access (Unknown Status Code: 507 (id: 223119309))
> Discarded access (Unknown Status Code: 507 (id: 223119363))
> Discarded access (Unknown Status Code: 507 (id: 241465157))
Connection failed
Database connection error: rolling back
Database connection error: terminate