Drop Ubuntu Precise 12.04 support

[Ben Shum]

Evergreen / OpenSRF master

With the merging of changes for bug 1551090 where we add support for Ubuntu Xenial (16.04) in the next major series of OpenSRF and Evergreen, we should officially plan to end support for Ubuntu Precise (12.04). The community only supports latest LTS and previous, so Xenial 16.04 + Trusty 14.04 moving forward with the next releases.

[Ben Shum (bshum)]

For Evergreen: user/bshum/ubuntu-cleanup-remove-precise

http://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/bshum/ubuntu-cleanup-remove-precise

For OpenSRF: user/bshum/ubuntu-cleanup-remove-precise

http://git.evergreen-ils.org/?p=working/OpenSRF.git;a=shortlog;h=refs/heads/user/bshum/ubuntu-cleanup-remove-precise

(note for the OpenSRF branch, I just realized that I have a few cleanup doc changes in that branch, only the top change affects removal of Precise, but we should grab and merge the other README changes too)

[Mike Rylander (mrylander)]

I've picked the Evergreen branch into master, thanks! (Leaving the OpenSRF one alone -- probably should be a bug on that LP project instead of here.)

[Galen Charlton (gmc)]

OpenSRF bits pushed to master for inclusion in 2-5-alpha. Thanks, Ben!