Remove the old (experimental) backup API.

The POST-based state API endpoint turned out to be incorrect.  Furthermore,
no client method was ever added to make use of the server-side method.
Merge pull request #492 from ericsnowcurrently/1.20-remove-old-backup

Remove the old (experimental) backup API.

The POST-based state API endpoint turned out to be incorrect.  Furthermore,
no client method was ever added to make use of the server-side method.

(same PR against master: https://github.com/juju/juju/pull/482)
Backport: Updating goyaml and goamz versions to latest.

Conflicts:
	agent/format-1.16.go
	agent/format-1.18.go
	cmd/juju/get_test.go
	cmd/juju/status_test.go
	container/lxc/lxc_test.go
	dependencies.tsv
	environs/configstore/disk.go
	juju/testing/conn.go
	provider/common/state.go
	provider/common/state_test.go
	worker/uniter/uniter_test.go
Merge pull request #522 from katco-/v1.20-backport

Backport: Updating goyaml and goamz versions to latest.

Conflicts:
	agent/format-1.16.go
	agent/format-1.18.go
	cmd/juju/get_test.go
	cmd/juju/status_test.go
	container/lxc/lxc_test.go
	dependencies.tsv
	environs/configstore/disk.go
	juju/testing/conn.go
	provider/common/state.go
	provider/common/state_test.go
	worker/uniter/uniter_test.go
Increment stable to 1.20.5 for internal release.
Merge pull request #526 from sinzui/inc-1.20.5

Increment stable to 1.20.5 for internal release.

A1.20.4 tarball was uploaded to Lp for testing...Lp will never let anyone upload the real 1.20.4. We need to increment.