read_only_rootfs_systemd: drop old tmpfiles bits

Signed-off-by: Christopher Larson <kergoth@gmail.com>
Revamp the way we set up the bind mounts

- Drop some legacy remnants
- Drop mount-binds and ro-binds in favor of volatile-binds, which is
  implemented quite differently. Rather than having a single service file
  which tries to do everything, and which only gets installed for read only
  images, now we generate per-mount service files with appropriate mount based
  dependencies, which integrate much better, and which are configured with
  a conditional such that they only run based on the rootfs being read only.
- Fix the failure to start systemd-random-seed.service.
- Ensure that /media is also writable, for udisks automount of media.
- Update readme to match the current state of the layer.

JIRA: SB-1504, SB-1351

Signed-off-by: Christopher Larson <kergoth@gmail.com>
volatile-binds: support for files as well as dirs

JIRA: SB-1386

Signed-off-by: Christopher Larson <kergoth@gmail.com>
Merge pull request #2 from kergoth/revamp-binds

Revamp the way we set up the bind mounts
connman: include an empty resolv.conf

Ensure that an empty resolv.conf exists before connman writes to it. This way
we have it in place in the read-only /, and we can bind mount over it.

JIRA: SB-1386

Signed-off-by: Christopher Larson <kergoth@gmail.com>
volatile-binds: bind mount /etc/resolv.conf

JIRA: SB-1386

Signed-off-by: Christopher Larson <kergoth@gmail.com>
Merge pull request #3 from kergoth/writable-resolv-conf

Make /etc/resolv.conf writable for read-only-rootfs
README.md: mention /etc/resolv.conf in the usage info
layer.conf: drop remnant of old implementation
TODO.md: Update
Merge remote-tracking branch 'origin/release/2013.11'

* origin/release/2013.11:
  TODO.md: Update
  layer.conf: drop remnant of old implementation
  README.md: mention /etc/resolv.conf in the usage info
  volatile-binds: bind mount /etc/resolv.conf
  connman: include an empty resolv.conf
  volatile-binds: support for files as well as dirs
  Revamp the way we set up the bind mounts
  read_only_rootfs_systemd: drop old tmpfiles bits