* tools/terraform-bundle: refactor to use new provider installer and
provider directory layouts
terraform-bundle now supports a "source" attribute for providers,
uses the new provider installer, and the archive it creates preserves
the new (required) directory hierarchy for providers, under a "plugins"
directory.
This is a breaking change in many ways: source is required for any
non-HashiCorp provider, locally-installed providers must be given a
source (can be arbitrary, see docs) and placed in the expected directory
hierarchy, and the unzipped archive is no longer flat; there is a new
"plugins" directory created with providers in the new directory layout.
This PR also extends the existing test to check the contents of the zip
file.
TODO: Re-enable e2e tests (currently suppressed with a t.Skip)
This commit includes an update to our travis configuration, so the terraform-bundle e2e tests run. It also turns off the e2e tests, which will fail until we have a terraform 0.13.* release under releases.hashicorp.com. We decided it was better to merge this now instead of waiting when we started seeing issues opened from users who built terraform-bundle from 0.13 and found it didn't work with 0.12 - better that they get an immediate error message from the binary directing them to build from the appropriate release.
