Conversion - Nested initialization

[AlexB52]

Currently Rubocop doesn't parse nested array appropriately.
Here are examples after the setup conversion.

They seem off and probable makes some ruby-specs fail resulting in skipping some of them.

# nested arrays
ary = [Grizzly::Collection[1, 2, 3]]
Grizzly::Collection[].flatten.should be_an_instance_of(Grizzly::Collection)
Grizzly::Collection[1, 2, 3].flatten.should be_an_instance_of(Grizzly::Collection)
Grizzly::Collection[1, [2], 3].flatten.should be_an_instance_of(Grizzly::Collection)
Grizzly::Collection[1, [2, 3], 4].flatten.should == [1, 2, 3, 4]
[Grizzly::Collection[1, 2, 3]].flatten.should be_an_instance_of(Grizzly::Collection)

# arrays with variables
[1, z, 6].flatten!.should == [1, 2, 3, 4, 5, 6]