Moved Flash detection to JS

There are a few distinct but related changes here but they made sense to
just tackle together.

Moved Flash detection (including Flash version parsing) into JavaScript.
Fixes #138.

Added new `deactivatedFlash` and `overdueFlash` events. These will be
changed to an `error` event type in the future along with `noFlash`,
`wrongFlash`, etc.
Fixes #255.

Standardized non-elemental events to all have `window` as the context
(`this`). Fixes #107.

Removed deprecated `ZeroClipboard.detectFlashSupport` method. Fixes #198.