Ubuntu system image 2.3

2.3 (2014-07-16)
================
 * Support factory resets. `system-image-cli --factory-reset` and a new D-Bus
   API method `FactoryReset()` are added. (LP: #1207860)
 * Data file checksums are passed to ubuntu-download-manager where available.
   (LP: #1262256)
 * Certain duplicate destinations are allowed, if they have matching source
   urls and checksums. (LP: #1286542)
 * When system-image-{cli,dbus} is run as non-root, use a fallback location
   for the log file if the system log file isn't writable. (LP: #1301995)
 * `system-image-cli --list-channels` lists all the available channels,
   including aliases. (LP: #1251291)
 * `system-image-cli --no-reboot` downloads all files and prepares for
   recovery, but does not actually issue a reboot. (LP: #1279028)
  * `system-image-cli --switch <channel>` is a convenient alias for
    `system-image-cli -b 0 -c <channel>`. (LP: #1249347)
 * Added `--show-settings`, `--get`, `--set`, and `--del` options for viewing,
   changing, and setting all the internal database settings. (LP: #1294273)
 * Improve memory usage when verifying file checksums. Given by Michael
   Vogt. (LP: #1271684)
 * In the `UpdatePaused` signal, return a percentage value that's closer to
   reality than hardcoding it to 0. (LP: #1274131)
 * New D-Bus API method `.Information()` which is like `.Info()` except that
   it returns extended information details, as a mapping of strings to
   strings. These details include a `last_check_date` which is the ISO 8601
   timestamp of the last time an `UpdateAvailableStatus` signal was sent.
   (LP: #1280169)
 * Set the GSM flag in ubuntu-download-manager based on the current s-i
   download setting. (LP: #1339157)
 * The system-image-dbus(8) manpage now describes the full D-Bus API. (LP:
   #1340882)
 * Fix the D-Bus mock service so that the downloading flag for
   `UpdateAvailableStatus` will correctly return true when checking twice
   under manual downloads. (LP: #1273354)
 * Pay down some tech-debt. (LP: #1342183)