Unit address from the machines watcher only

Unit address from the machines watcher only

Only use the mega-watcher for machines to retrieve
the Juju GUI unit address.
This change has several consequences:
- it allows us to apply some logic on how the
  right address is chosen. For instance, now
  we try to resolve public hostnames before
  proceeding, and this should fix the cases
  where a cloud dns is not configured on the 
  machine running quickstart. This is the case
  of many maas environments;
- it simplifies parsing the mega-watcher changes;
- more importantly, it breaks compatibility
  with very old versions of juju (<1.18), in which
  the mega-watcher for machines did not include
  machine addresses.

For this reason, quickstart now explicitly
drops support for juju < 1.18.1 
(1.18.1 is the version on trusty universe).

This also allows for removing some version
checks in the code, including sudo handling when
calling bootstrap on local envs, several special
cases on the watcher side, and other oddities.

For the reasons above, I bumped the quickstart
version up to 1.5.0.

PS: my apologies for the long diff, hope the code
is still easy to follow. Sorry.

Tests: `make check`

QA:
run quickstart as usual, on local and cloud envs,
check it works properly when run again, etc.
this branch has been already successfully QAed in 
a maas environment by Adam (Landscape team).

https://code.launchpad.net/~frankban/juju-quickstart/maas-address/+merge/241263

(do not edit description out of merge proposal)

[frankban, 2014-11-10 12:30:34]

Please take a look.

[bac, 2014-11-10 14:31:29]

On 2014/11/10 12:30:34, frankban wrote:
> Please take a look.

LGTM. Have not done QA yet.

[bac, 2014-11-10 15:23:50]

QA OK

[rharding, 2014-11-10 15:25:20]

LGTM ty for the updates!

https://codereview.appspot.com/174790043/diff/1/quickstart/app.py
File quickstart/app.py (left):

https://codereview.appspot.com/174790043/diff/1/quickstart/app.py#oldcode188
quickstart/app.py:188: if requires_sudo:
is this because of the new juju requirement?

[frankban, 2014-11-10 15:30:01]

Thank you both for the reviews of this long diff!

https://codereview.appspot.com/174790043/diff/1/quickstart/app.py
File quickstart/app.py (left):

https://codereview.appspot.com/174790043/diff/1/quickstart/app.py#oldcode188
quickstart/app.py:188: if requires_sudo:
On 2014/11/10 15:25:20, rharding wrote:
> is this because of the new juju requirement?

Yes! We got rid of very old versions of juju requiring an explicit sudo on the
command line.

[frankban, 2014-11-10 15:31:59]

*** Submitted:

Unit address from the machines watcher only

Only use the mega-watcher for machines to retrieve
the Juju GUI unit address.
This change has several consequences:
- it allows us to apply some logic on how the
  right address is chosen. For instance, now
  we try to resolve public hostnames before
  proceeding, and this should fix the cases
  where a cloud dns is not configured on the 
  machine running quickstart. This is the case
  of many maas environments;
- it simplifies parsing the mega-watcher changes;
- more importantly, it breaks compatibility
  with very old versions of juju (<1.18), in which
  the mega-watcher for machines did not include
  machine addresses.

For this reason, quickstart now explicitly
drops support for juju < 1.18.1 
(1.18.1 is the version on trusty universe).

This also allows for removing some version
checks in the code, including sudo handling when
calling bootstrap on local envs, several special
cases on the watcher side, and other oddities.

For the reasons above, I bumped the quickstart
version up to 1.5.0.

PS: my apologies for the long diff, hope the code
is still easy to follow. Sorry.

Tests: `make check`

QA:
run quickstart as usual, on local and cloud envs,
check it works properly when run again, etc.
this branch has been already successfully QAed in 
a maas environment by Adam (Landscape team).

R=bac, rharding
CC=
https://codereview.appspot.com/174790043