Implement landscape layout for time picker dialog

Adds support overriding default alert dialog panel elements by including
them in the dialog's custom content view, but no public API (yet!) since
the panel IDs have never been public. Some minor cleanup and refactoring
in TimePickerDialog. Removes Holo styles for "clock" and "calendar" style
pickers since they are new in Material. If the new styles are used against
Holo they will match Material but with Holo primary/accent colors.

Also implements themed color state lists to resolve TODOs in both time
and date pickers.

Bug: 19431361
Change-Id: I095fd8d653e02d9e5d20d66611432a08a7a5685e