Remove asciidoc Ansible dependencies

Maybe this will make Travis CI less prone to errors
Another update of Ansible dependencies

After testing in Ubuntu 12.04 VM instance and finding
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=564579 it looks like
combination of 'asciidoc' and 'xmlto' packages should fix random errors
in Travis builds. Hopefully.
Merge pull request #39 from drybjed/travis

Remove asciidoc Ansible dependencies