Merge ~smoser/cloud-init:feature/curtin-centos4 into cloud-init:master

[Scott Moser]

sysconfig: fix rendering of bond, bridge and vlan types.

Previously, virtual types (bond, bridge, vlan) were almost completely broken.
They would not get any network configuration (ip addresses or dhcp config)
and or routes rendered. This fixes those issues.

For bonds we now correctly render BONDING_SLAVE entries.

LP: #1695092

[Scott Moser (smoser)]

i plan on adding a vlan and a simple bridge test

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:50912bf294eced2b825c7ed93ff9be98b43feda3
https://jenkins.ubuntu.com/server/job/cloud-init-ci/60/
Executed test runs:
    SUCCESS: Checkout
    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    SUCCESS: CentOS 6 & 7: Build & Test
    IN_PROGRESS: Declarative: Post Actions

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/60/rebuild

review: Approve (continuous-integration)

[Server Team CI bot (server-team-bot)]

FAILED: Continuous integration, rev:5f364ce26a6d5544718ec5e961d3d0a3cdb75bae
https://jenkins.ubuntu.com/server/job/cloud-init-ci/61/
Executed test runs:
    SUCCESS: Checkout
    FAILED: Unit & Style Tests

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/61/rebuild

review: Needs Fixing (continuous-integration)

[Ryan Harper (raharper)]

review: Approve

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:c8129c6a9717ce74cf81f00fd5c2ac85730f8b7c
https://jenkins.ubuntu.com/server/job/cloud-init-ci/62/
Executed test runs:
    SUCCESS: Checkout
    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    SUCCESS: CentOS 6 & 7: Build & Test
    IN_PROGRESS: Declarative: Post Actions

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/62/rebuild

review: Approve (continuous-integration)

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:51febf7363692d7947fe17a4fbfcb85058168ccb
https://jenkins.ubuntu.com/server/job/cloud-init-ci/65/
Executed test runs:
    SUCCESS: Checkout
    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    SUCCESS: CentOS 6 & 7: Build & Test
    IN_PROGRESS: Declarative: Post Actions

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/65/rebuild

review: Approve (continuous-integration)