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.
Maybe I don't find it, but would like to see a test where `SocketTimeout` is corrected to the minimum value.