o.c.dal2: avoid synchronous requests inside callbacks from pv access
o.c.dal2: Added Test
o.c.archive.common: Fixed visualization of timestamps
o.c.archive.common: Use C3P0 connection pool instead of own pooling
o.c.dal2: Minor fixes
Merge remote-tracking branch 'origin/rel15x_beta_dal2' into rel15x_beta_dal2