Add support for Ubuntu 15.04

[eheydrick]

Ubuntu 15.04 is out, would be nice to have bento boxes for test-kitchen.

[juliandunn]

@fnichol ping

[fnichol]

Confirmed! I took a spike at this earlier this week and now that the ISO bits are in GA I will circle back on this.

[thasmo]

Would be awesome to also have a base box available for Vagrant on Atlas.

[arosenhagen]

@thasmo FYI: just pushed an update to https://github.com/ffuenf/vagrant-boxes

[andrewhood125]

👍

[fnichol]

Work is ongoing in #349 which will close this issue once merged.

Sadly it seems as the VMware Fusion and Parallels can't yet compile their tools against the 3.19.x Linux kernel. There are links in #349 for tracking.

[thasmo]

@fnichol, thanks for the update! :)