Rename retreive to retrieve.
Replace icontrol with savon, and repair some providers.

The original icontrol gem relies on the built in ruby SOAP stuff to do
it's magic but this was removed in ruby 1.9.  It's possible to add back
in but it's easier to switch to savon which works across 1.8-2.1.

The icontrol gem is basically an extremely thin wrapper around the wsdl
files with a couple of methods to initialize the SOAP connections, so
we're able to easily update it to use Savon.

Once that's done we repair several providers to work with Savon and
implement the beginnings of unit testing for f5_user.
Merge pull request #114 from apenney/savon-implementation

Savon implementation