(#215) Add support for IP range

Add support for filtering by source and destination IP range, equivalent to '-m iprange --src-range|--dst-range',
which is only allowing a specified IP range. Excluding an IP range, '! --src-range or ! --dst-range', is not supported.

Add ':src_range' and ':dst_range' to firewall.rb
(#215) Add support for IP range

Add support for filtering by source and destination IP range, equivalent to '-m iprange --src-range|--dst-range',
which is only allowing a specified IP range. Excluding an IP range, '! --src-range or ! --dst-range', is not supported.

Add ':src_range' and ':dst_range' to iptables.rb
Add specs for dst_range and src_range params
Remove travis testing puppet 2.6
Merge pull request #218 from hunner/remove_puppet_2.6

Remove travis testing puppet 2.6
Update providers to use expect syntax

The expect syntax is much better than the should syntax and ships with
RSpec 2.14. It caused a few conflicts with the mocha stubbing, so I
updated the docs to use rspec test doubles instead.
Add SL and SLC cases for operatingsystem
Merge pull request #217 from hunner/update_provider_specs

Update providers to use expect syntax
Merge pull request #220 from traylenator/SLC

Add SL and SLC cases for operatingsystem
Add rspec-system tests for src_range/dst_range
Merge pull request #219 from hunner/feature/master/add-support-for-iprange

Feature/master/add support for iprange