Upgrade Ember to 3.28 #166

Job	Run time
Lint	28s
Tests (ubuntu-latest, chrome)	53s
Floating Dependencies (ubuntu-latest, chrome)	1m 0s
Tests - ember-lts-2.12	1m 24s
Tests - ember-lts-2.18	1m 17s
Tests - ember-lts-3.16	1m 58s
Tests - ember-lts-3.20	1m 54s
Tests - ember-lts-3.24	1m 19s
Tests - ember-lts-3.28	1m 33s
Tests - ember-lts-4.4	1m 43s
Tests - ember-lts-4.8	1m 19s
Tests - ember-3.28-with-jquery	1m 16s
Tests - ember-3.28-classic	1m 18s
Tests - ember-canary	1m 30s
	18m 52s

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