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 debian-trusty
Bump version to 0.15.2-1~trusty

Signed-off-by: Nikos Skalkotos <skalkoto@grnet.gr>