Typo :(
Pull warmup and run into IPSJob

Benchmark.ips is so big. IPSJob should know how to run a warmup and run
function on it's list of items. Further refactoring needed.
Add more knowledge to IPSJob

In order to easily run the warmup and run methods, IPSJob should know
about the suite, quiet, warmup and time parameters. Add these as part of
the initialization step and utilize in both of these new methods.
Add compare? to IPSJob

It looks better than just compare alone.
Fix run method

Need to actually return the list of reports (d'oh!)
Add compare! to README and benchmark_ips

Add brief documentation about the compare! method to the README, and add
it to the default addition comparision in benchmark_ips to more easily
test that all things are running correctly.
Add configuration options

The Benchmark.ips(5,2) syntax is vague and difficult to understand.
While keeping this syntax in place, add an additional ability to
configure these options within the block itself by calling `config` on
the underlying IPSJob object and pass in a hash with :time and :warmup
symbols. Also add this to README and example script.