Foreman installation on amazon ec2 instance

Hi there and thank you for reading,

I am currently in the process of setting up a puppet service for our ec2 instances and decided to give foreman a try (node certificate management and automatic passenger setup seems nice).

Unfortunately I'm running into difficulties with the installation. I'm on fresh a 'Amazon Linux AMI x86_64 PV':

[root@hostname ~]# uname -a
Linux hostname 3.10.35-43.137.amzn1.x86_64 #1 SMP Wed Apr 2 09:36:59 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

and tried the following:

sudo yum -y update
sudo yum -y install http://yum.theforeman.org/releases/1.1/el6/x86_64/foreman-release.rpm
sudo yum -y install foreman-installer

which results in this:

Error: Package: rubygem-foreman_api-0.1.11-1.el6.noarch (foreman)
       Requires: rubygem(rest-client) >= 1.6.1
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest

The suggestions seem useless (–skip-broken installs all dependencies but foreman/puppet).
I ended up here
and tried installing the repository (after removing the old one)

sudo yum -y remove epel-release
sudo yum -y install http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

now again, what I tried:

sudo -y update
sudo -y install foreman-installer

results in the same error.
Installation without previous update is possible (though yum will complain about Public keys) and results in the following error:

[ec2-user@hostname ~]$ foreman-installer
/usr/share/ruby/vendor_ruby/2.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- highline/import (LoadError)
        from /usr/share/ruby/vendor_ruby/2.0/rubygems/core_ext/kernel_require.rb:55:in `require'
        from /usr/sbin/foreman-installer:3:in `<main>'

I had similar problems while trying to set up passenger and eventually surrendered. I assume this happens due to conflicting ruby version, so:

[root@hostname puppet]# ruby --version
ruby 2.0.0p451 (2014-02-24 revision 45167) [x86_64-linux]
[root@hostname puppet]# gem --version
2.0.14
[root@hostname puppet]# ls /usr/bin | grep ruby
ruby
ruby1.8
ruby2.0
[root@hostname puppet]# ls /usr/bin | grep gem
gem
gem2.0

Did someone run into the same issues? How do I resolve this?

Thanks in advance and thank you for reading through all this!