Bump version to 0.15.2
Merge AM_INIT_AUTOMAKE entries in configure.ac

Newer versions of automake raise errors when multiple AM_INIT_AUTOMAKE
entries are defined.
Update ChangeLog and version files version 0.15.2
Merge branch 'hotfix-0.15.2'
Merge branch 'master' into develop

Bump version to 0.15.2next

Conflicts:
	docs/version.py
	version
	version.m4
docs: Add instructions for Ubuntu 14.04

Drop support for installing snf-image packages in Ubuntu 12.04 LTS and
add support for 14.04