Address warnings

The 2-99-maintenance branch was spewing tons of deprecation warnings.  I also discovered that the source line being printed in some deprecation messages was wrong, so I fixed that.  Finally, I realized that there is a situation where the `any_instance` receiver block arg deprecation warning wasn't needed, so I changed it to not print in that case: when the block ignores args (e.g. `allow_any_instance_of(MyClass).to receive(:foo) { 5 }`) it doesn't matter that RSpec 3 will include an extra arg.