make all instance methods available during recording

this removes the need to redundantly include modules (e.g. FactoryGirl)
into Onceler; whatever is available to your specs will be available to
onceler, since we now record directly onto an instance of the example
group. this also lets us get rid of the group proxy thingy, and reduces
overhead, since we're doing way fewer define_method calls.
add identity spec
v0.0.7
expose some useful state
not needed anymore
v0.0.8
allow onces to override inherited eaches
v0.0.9