delete testing/filetesting; use github.com/testing/filetesting instead
Start using networks constraints for deployments:
- "juju deploy" uses --networks=net1,net2 argument to specify
  requested networks (required to be enabled), while "softer"
  requrements only for instance selection can be given with
  --constraints networks=net2,^net3 (positive and negative)
- updated help topics
- changed MachineConfig to only have Networks (to include)
- changed RequestedNetworks in state for machines and services
  to have only a list of included networks
- changes in the MAAS provider to use both requested networks
  and network constraints for acquireNode
- provisioner API and worker uses requested networks as
  from a single slice, and ProvisioningInfo-related code was
  updated similarly
- juju status changed to show only requested networks as enabled
  and networks from constraints as disabled for a service
- fixes in lots of places (mostly tests)

There are a lot of changed files, but most of them are just
fixed tests and code using NewMachineConfig or AddService,
whose arguments have changed.
sortimports
Merge remote-tracking branch 'origin/master' into 003-remove-filetesting

Conflicts:
	utils/zip/zip_test.go
	worker/uniter/charm/manifest_deployer_test.go
	worker/uniter/relationer_test.go
	worker/uniter/uniter_test.go
Fixed conflicts and merged master
Merge pull request #13 from dimitern/501-use-networks-constraints

- in "juju deploy"
- update help topics
- change MachineConfig to only have Networks (to include)
- change RequestedNetworks in state for machines and services
  to have only a list of included networks
- changes in the MAAS provider to use both requested networks
  and network constraints for acquireNode
- provisioner API and worker uses requested networks as
  from a single slice, and ProvisioningInfo-related code was
  updated similarly
- fixes in lots of places (mostly tests)

There are a lot of changed files, but most of them are just
fixed tests and code using NewMachineConfig or AddService,
whose arguments have changed.
Merge remote-tracking branch 'origin/master' into 003-remove-filetesting
Merge pull request #31 from rogpeppe/003-remove-filetesting