Increase socket timeout to 1 minute during bootstrap

We increase the socket timeout during bootstrap to
cope with slow disk I/O during machine initialisation.
Empirical evidence has shown this to decrease the
bootstrap failure rate on Microsoft Azure.

Fixes https://bugs.launchpad.net/juju-core/+bug/1351101
cmd/jujud: add test for InitializeState params
cmd/jujud: set socket timeout to bootstrap timeout
cmd/jujud: add test to ensure SocketTimeout is set to minimum
Merge pull request #484 from axw/lp1351101-bootstrap-longsockettimeout-master

Cherry picks from 1.20 to fix Azure bootstrap

Fixes https://bugs.launchpad.net/juju-core/+bug/1350983

Changes:

dd02d1e (Andrew Wilkins, 4 days ago)
   cmd/jujud: set socket timeout to bootstrap timeout

04cb3b7 (Andrew Wilkins, 4 days ago)
   cmd/jujud: add test for InitializeState params

14561dc (Andrew Wilkins, 4 days ago)
   Increase socket timeout to 1 minute during bootstrap

   We increase the socket timeout during bootstrap to cope with slow disk I/O
   during machine initialisation. Empirical evidence has shown this to
   decrease the bootstrap failure rate on Microsoft Azure.