Fix bug where a new TerminalViewer would be removed from the DOM at the wrong time and then not accept focus.
Fix bug where a new TerminalViewer would be removed from the DOM at the wrong time and then not accept focus.

Fixes issue #60

sedwards2009/extraterm,sedwards2009/extraterm,sedwards2009/extraterm,sedwards2009/extraterm,sedwards2009/extraterm