Modify logs to include timestamps

[hvelarde]

Currently stderr and stdout logs are less than useless if you want to analyze them after a problem has happened because they don't include timestamps and you have no idea when a certain event took place.

Take, for instance the piece of memmon error log I included on a previous issue (#70):

Checking groups app=1610612736
RSS of app:instance1 is 1614974976
Restarting app:instance1
RSS of app:instance2 is 1297457152
RSS of app:instance3 is 1477554176
Checking groups app=1610612736
RSS of app:instance1 is 318668800
RSS of app:instance2 is 1297506304
RSS of app:instance3 is 1477554176
Checking groups app=1610612736
RSS of app:instance1 is 164720640
RSS of app:instance2 is 1297575936
RSS of app:instance3 is 1477672960
Checking groups app=1610612736
RSS of app:instance1 is 340303872
RSS of app:instance2 is 1305280512
RSS of app:instance3 is 1477713920
Checking groups app=1610612736
RSS of app:instance1 is 166830080
RSS of app:instance2 is 1318711296
RSS of app:instance3 is 1477849088
Checking groups app=1610612736
RSS of app:instance1 is 337248256
RSS of app:instance2 is 1325903872
RSS of app:instance3 is 1477685248

The httpok error log of that process gives me no indication of when the restarts happened, so I can not associate this information with the other:

Restarting selected processes ['app:instance1']
app:instance1 is in RUNNING state, restarting
app:instance1 restarted
Restarting selected processes ['app:instance1']
app:instance1 is in RUNNING state, restarting
app:instance1 restarted
Restarting selected processes ['app:instance1']
app:instance1 is in RUNNING state, restarting
app:instance1 restarted