double the screen sleep timeout

HP Cloud 1.1 is quite slow per core. So much so that grenade is
often failing to start services because bash in a screen session
isn't ready in 1.5s. Double this to 3s to try to decrease failures
in the gate.

We should instead do this via some readiness check to decrease
races.

(cherry picked from commit 43d8f1cdddee5ed20dfef267dc59f7c4805d3a75)

Conflicts:
	functions-common

Change-Id: I2b066a687916742e966190f00b5b06a795d4a014
convert devstack from awk to outfilter

The complexity of the awk script was pretty high, and it would
be good to do it in summaries as well, which starts to get a bit
squirelly. Instead bring over the outfilter.py from grenade and
use it for the timestamping.

Any additional overhead from python should be offset from not
shelling out to date on every line of output.

(cherry picked from commit 62cb563ddc5f6923a9734a96d394ff2c27c320ca)

Conflicts:
	stack.sh

Change-Id: Ic2b86ddba3e7f6520a0fd35599b01143936c6deb