Strip carriage returns from .travis.yml

git-svn-id: http://svn.osgeo.org/postgis/trunk@12266 b70326c6-7e19-0410-871a-916f4a2858ee
Do not use ubuntugis-unstable

Also, search for libgdal and postgresql-server

git-svn-id: http://svn.osgeo.org/postgis/trunk@12267 b70326c6-7e19-0410-871a-916f4a2858ee