Make executor threads more robust

See bug #1189711

Prevent the executor thread getting killed by exceptions.

Change-Id: I0787fa619a6a8a35a303627f8ce119c93f2c8765
More server work

Change-Id: If8c2aa6c83ea6c42ff468c5b2560805dd653c056
Implement connection pooling

Change-Id: Ifcc04bbfee2fbd6a7531516094ba42b6dc863ee2