Fix a non-deterministic test bug

Test was relying on map order.
Remove instance.(Wait)DNSName

Because we don't need them, and I'm sick of seeing them.
Merge pull request #38 from axw/remove-instance-dnsname

Because we don't need them, and I'm sick of seeing them.

Also, drive-by fix for a non-deterministic test that fails with Go 1.3 beta 2.
Update to use new base txn struct
Introduce new txn package and move transaction functionality from state
Revert resource catalog wor as this will be done downstream from the changes in this branch

This reverts commit 3f07858066fca5e9b5c167616988d7d87a618c4f.
Fix typo
Add back deleted files from previous merge
Add tests for put/remove races
Merge branch 'environ-resource-catalogs' of https://github.com/wallyworld/juju into environ-resource-catalogs