Update decreaseIndentPattern to match Atom

[kaidamasaki]

Atom's decreaseIndentPattern handles cases like this:

@date = Date.today()
@name = "Test Name"

@data = {
  id: 8,
  foo: Foo.new(
    id: 1,
    phone_number: "412-555-7640"
  ),
  bar: Bar.new(
    id: 1,
    name: "Valentine",
    vin: "DF5S6HFG365HGDCVG",
    status: :AVAILABLE
  ),
  start_time: start_time.to_s,
  end_time: end_time.to_s,
  cost: 23.45,
  rating: 3,
}