Provide a means to measure raw servlet perf on Immutant

Unfortunately, we can't do this by default without firing up two
instances of Immutant since the tests expect a dedicated port for each
app. Despite this being an uncommon deployment configuration, I was
interested enough in Immutant's relative performance to provide an
inactive :servlet profile that invokes the same servlet used in the
other servlet-based tests. I'm still not sure this should be encouraged,
however. :)
Update cpuinfo and include Immutant servlet perf in graph