Put open icon back for inputDate and inputDateTime on mobile.
@bug W-1890703@
datePicker - Change "Today" link to button to workaround a double click bug.
@bug W-1883366@

Conflicts:

	aura-components/src/main/components/ui/datePicker/datePicker.css
	aura/src/test/java/org/auraframework/components/ui/inputDate/InputDateWithLabelUITest.java
Fix InputDateWithLabelUITest caused by "Today" change.

Conflicts:

	aura/src/test/java/org/auraframework/components/ui/inputDate/InputDateWithLabelUITest.java
datePicker - change html button to ui:button.
@bug W-1893768@

Conflicts:

	aura/src/test/java/org/auraframework/components/ui/inputDate/InputDateWithLabelUITest.java
Merging origin/ssun/master-pending-merge186patch into master