Cop idea: no context for single `it` block

[mockdeep]

One thing we try to do, when we remember, is to collapse context descriptions when there is a single it block:

# bad
context 'when this thing' do
  it 'does something'
end

# good
it 'does something when this thing' do
end

# also okay
context 'when this thing' do
  it 'does something'
  it 'does something else'
end