Feature timewarp parse date 867 (#951)

* Working on tests for timewarp --parse-date

* Test working for --parse-date

* Refactored date utils out of timewarp.py

* Added timezone to --parse-date, updated tests

* Added cog to README

tests/TestTimeWarp-13.1.0.photoslibrary/private/com.apple.Photos/appPrivateData.plist

@@ -4,5 +4,10 @@
 <dict>
 	<key>CollapsedSidebarSectionIdentifiers</key>
 	<array/>
+	<key>IPXWorkspaceControllerZoomLevelsKey</key>
+	<dict>
+		<key>kZoomLevelIdentifierPhotosGrid</key>
+		<integer>2</integer>
+	</dict>
 </dict>
 </plist>