New 15.04 stable release

[Michael Vogt]

Hi all,

we are excited to announce a new Snappy Ubuntu Core stable release
(image 6 at 15.04/stable)!

Highlights of this release include:
- fix crash if coreconfig gets invalid config
- add basic support for uefi firmware updates

The stable images were also updated
(http://releases.ubuntu.com/15.04/) to reflect the latest image
available in the stable channel (you can also find them at
http://cdimage.ubuntu.com/ubuntu-snappy/15.04/stable/20151006/)

If you find any issue please make sure to use
https://bugs.launchpad.net/snappy/+filebug to report them, including
the device and image revision you're currently using.


Happy snapping,

 - Michael and the snappy team