player: create $el on initialize, add defaults
player: trigger show:<view> event on render
player: add show option to configure initial view

by default, non-new acorns show splash view. certain strings passed via
the `show` option will configure different behavior:
* editor[-single]: show editor. optionally show a simplified
  single-shell editor.
* content[-<n>]: show content. optionally show splash for n milliseconds
  before showing content.