using __atom_ prefix.

Fixes issue #10.

@Savar - can you verify this works?
Merge branch 'bugs/http_url_encoding-atom'
fixes #6

Group and User are now system users
Merge branch 'feature/system-users'
Cherry-picking  a107146 which updates the format for downloading rpms/debs
fixing funny params and faulty paren
group of log, lib and data dirs should be riak
ulimit simple implementation

Should solve it for CentOS (tested).

Neither /etc/pam.d/common-session, nor /etc/default/riak
are modified, but they might have to be; see
https://github.com/basho/riak-chef-cookbook/commit/41661c227e1a985a52ee87678a91588d05fbe372
and
http://docs.basho.com/riak/latest/cookbooks/Open-Files-Limit/.
Merge pull request #17 from basho/feature/ulimit-centos

ulimit simple implementation

This relates to issue #13 - @Iristyle - could you check which of the options - `/etc/default/riak` or `/etc/pam.d/common-session` should be used and whether that differs between versions of debian/ubuntu?
upgraded vagrantfile
Merge remote-tracking branch 'origin/feature/hash-merging' into maint/upgrade-vagrant
working merging