Gem install fails on Ruby 1.8.7

[rickard-von-essen]

Installing fails on EL 6 (Ruby 1.8.7) on nokogiri.

If ruby 1.8 support have been dropped it should be nice to state it in the README and provide some simple pointers on how to install 1.9 on EL.

$ gem install cucmber-nagios
...
Fetching: cucumber-1.3.15.gem (100%)
Fetching: rspec-support-3.0.0.gem (100%)
Fetching: rspec-core-3.0.0.gem (100%)
Fetching: rspec-expectations-3.0.0.gem (100%)
Fetching: rspec-mocks-3.0.0.gem (100%)
Fetching: rspec-3.0.0.gem (100%)
Fetching: mini_portile-0.6.0.gem (100%)
Fetching: nokogiri-1.6.2.1.gem (100%)
ERROR:  Error installing cucumber-nagios:
        nokogiri requires Ruby version >= 1.9.2.
$ ruby --version
ruby 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]
$ gem --version
1.8.10
$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.5 (Santiago)

See #66 Abandon Ruby 1.8.7: When?