Fix ruby 1.9 compatibility issue when loading free ip

[iNecas]

In Ruby 1.8.7:

{}.to_s # => ""

In Ruby 1.9.3

{}.to_s # => "{}"

This causes the url for smart proxy to be broken.

[domcleal]

Thanks, that looks good.

Could you please file an issue for it and write a test? There's a BMC API test file you could start from, so we begin getting coverage of this class.

[iNecas]

http://projects.theforeman.org/issues/2398

I would prefer somebody from the core team to write test cases for most of the dhcp api, as that would result it better tests than writing it by me, just for this case. It seems completion of tests for smart proxy is already in progress, I would like to avoid this PR to be part of the tests completion, and have this merged ASAP, since it's a bit blocker for Katello Foreman integration.