Ubuntu system image 3.0

3.0 (2015-05-08)
================
 * Support a built-in PyCURL-based downloader in addition to the traditional
   ubuntu-download-manager (over D-BUS) downloader. Auto-detects which
   downloader to use based on whether udm is available on the system bus,
   pycurl is importable, and the setting of the SYSTEMIMAGE_PYCURL environment
   variable. Initial contribution by Michael Vogt. (LP: #1374459)
 * Support alternative machine-id files as fall backs if the D-Bus file does
   not exist. Specifically, add systemd's /etc/machine-id to the list.
   Initial contribution by Michael Vogt. (LP: #1384859)
 * Support multiple configuration files, as in a `config.d` directory. Now,
   configuration files are named `NN_whatever.ini` where "NN" must be a
   numeric prefix. Files are loaded in sorted numeric order, with later files
   overriding newer files. Support for both the `client.ini` and
   `channel.ini` files has been removed. (LP: #1373467)
 * The `[system]build_file` variable has been removed. Build number
   information now must come from the `.ini` files, and last update date
   comes from the newest `.ini` file loaded.
 * The `-C` command line option now takes a path to the configuration
   directory.
 * Reworked the checking and downloading locks/flags to so that they will work
   better with configuration reloading. (LP: #1412698)
 * Support for the `/etc/ubuntu-build` file has been removed. The build
   number now comes from the configuration files. (LP: #1377312)
 * Move the `archive-master.tar.xz` file to `/usr/share/system-image` for
   better FHS compliance. (LP: #1377184)
 * Since devices do not always reboot to apply changes, the `[hooks]update`
   variable has been renamed to `[hooks]apply`. (LP: #1381538)
 * For testing purposes only, `system-image-cli` now supports an
   undocumented command line switch `--skip-gpg-verification`. Originally
   given by Jani Monoses. (LP: #1333414)
 * A new D-Bus signal `Applied(bool)` is added, which is returned in
   response to the `ApplyUpdate()` asynchronous method call. For devices
   which do not need to reboot in order to apply the update, this is the only
   signal you will get. If your device needs to reboot you will also receive
   the `Rebooting(bool)` command as with earlier versions. The semantics of
   the flag argument are the same in both cases, as are the race timing issues
   inherent in these signals. See the `system-image-dbus(8)` manpage for
   details. (LP: #1417176)
 * As part of LP: #1417176, the `--no-reboot` switch for
   `system-image-cli(1)` has been deprecated. Use `--no-apply` instead
   (`-g` is still the shortcut).
 * Support production factory resets. `system-image-cli --production-reset`
   and a new D-Bus API method `ProductionReset()` are added. Given by Ricardo
   Salveti. (LP: #1419027)
 * A new key, `target_version_detail` has been added to the dictionary
   returned by the `.Information()` D-Bus method. (LP: #1399687)
 * The `User-Agent` HTTP header now also includes device and channel names.
   (LP: #1387719)
 * Added `--progress` flag to `system-image-cli` for specifying methods for
   reporting progress. Current available values are: `dots` (compatible with
   system-image 2.5), `logfile` (compatible with system-image 2.5's
   `--verbose` flag), and `json` for JSON records on stdout. (LP: #1423622)
 * Support for the `SYSTEMIMAGE_DBUS_DAEMON_HUP_SLEEP_SECONDS` environment
   variable has been removed.
 * Fix `system-image-cli --list-channels`. (LP: #1448153)