Add protocol 6 Time spec for time in DST

[synthead]

Fixes #325!

This PR adds a spec to ensure that a time in DST is doing what it should.

From #325:

This PR fixed a bug where the time on the Beepwear Pro (protocol 6) was set one hour fast for a time in daylight savings time:

• Fix protocol 6 (Beepwear Pro) setting time 1 hour fast in daylight savings time #314

It removed this spec, since daylight savings time is now handled without any special circumstances:

timex_datalink_client/spec/lib/timex_datalink_client/protocol_6/time_spec.rb

Lines 136 to 143 in 7ca2154

	context "when time is in daylight savings time" do
	let(:tzinfo) { TZInfo::Timezone.get("US/Pacific") }
	let(:time) { tzinfo.local_time(2015, 10, 21, 19, 28, 32) }
	it_behaves_like "CRC-wrapped packets", [
	[0x32, 0x01, 0x20, 0x14, 0x1c, 0x0a, 0x15, 0x0f, 0x1a, 0x0e, 0x1e, 0x02, 0x18, 0x01, 0x00]
	]
	end

However, it'd still be good to have this spec in place to ensure that it isn't being treated with any special circumstances 👍