Replace LoggingSuite with BaseSuite

Replace LoggingSuite with BaseSuite

A mechanical change - the new BaseSuite is used
in place of LoggingSuite across the codebase. This
provides what LoggingSuite does but also ensures
no outgoing network connections are used and also
ensures the HOME var is cleared.

A couple of tests in cmd are left using LoggingSuite 
to make it easier to extract this package separate
to juju-core later.

https://code.launchpad.net/~wallyworld/juju-core/use-basesuite/+merge/220154

(do not edit description out of merge proposal)

[wallyworld, 2014-05-20 04:36:18]

Please take a look.

[axw, 2014-05-20 05:56:13]

On 2014/05/20 04:36:18, wallyworld wrote:
> Please take a look.

LGTM. I only looked at the first handful of files, and osenv/vars_test.go. I
assume the others are all more of the same.