Tweak the README

Now we point users to the `LICENSE.md` file for the license,
instead of including it in the README. This also removes the
example integrations, which are no longer officially maintained
by Select2.

The translation section has also been updated.
Move placing the sections into methods

This allows them to be overridden, allowing for things like
attaching the dropdown to a different part of the DOM.

The id is also now generated in a function that can be overridden.
Added decorator to remove the placeholder object

This will remove the placeholder object from the results list.
Fix automatically hiding the placeholder

The placeholder will not only be automatically hidden if the
results adapter was not already overridden. This will allow users
to override the results adapter to now hide the placeholder, if
they do not want that functionality.
Better support for tagging

This removes the special case for `<select>` elements and instead
handles everything tagging related within the `Tags` decorator.
Allow the position of the tag to be customized.
Move all of the event binding into separate methods

This should make it easier to override in subclasses.
Set up the click handler for closing

Now the dropdown will automatically be closed when the user clicks
outside of it.
Register the click handler in the container

This shouldn't be in the core, it's much easier to override things
in the container.
Move to a central key handler

This allows for any control to emit key events, and for the Select2
instance to handle them. So now the search box will allow for
results to be scrolled and selected, bringing back the old expected
functionality. This also stops triggering new queries when the
arrow keys are pressed.

The container will also be automatically focused when the dropdown
is closed, which is consistent with the old Select2.

The results will no longer be queried on initialization, but
instead will be queried when the dropdown is opened. This is more
consistent with the previous version of Select2.

The search box will now be cleared when the dropdown is closed.
Better key event handling
Working on remote data sets

This starts work on the example, which currently uses the GitHub
API.

The `ajax.delay` option has been added that allows for debouncing
requests made within a certain number of milliseconds.
Added basic templating to results
Bring over the repo results formatter
Templating for selections
Handle `minimumInputLength`