Cop idea: detect calling of a mock inside the example

[Darhazer]

I know this is weird, but I've seen code such as

expect(Foo).to receive(:bar).and_return(:baz)
expect(subject.baz).to eq Foo.bar

(one very interesting example was expect(Account).to receive(:all).once.and_return(Account.all)) Such strange misuses of mocks could be detected by rubocop-rspec

[pirj]

Related to #221, (will supposedly be) fixed in #226.