Added oauth authentication with WordPress.com to dashboard.

The quickstart dashboard plugin is now able to handle a connection with
WordPress.com through oauth.
Refactored oath flow into its own function due to the large block of code.
Adding VIPThemeHelper to Quickstart Dashboard.

The `VIPThemeHelper` is a dashboard plugin that is able to query
WordPress.com VIP for the users' VIP themes. Once it has a list of themes
it can prompt the user to install them automatically. It does this by
doing an `svn checkout` of the theme into `themes/vip/$theme`.

After a theme is checked out, it is able to both network activate and
switch the current theme to that theme for the user, making setting up
themes very simple. In most cases, the installation and activation is done
as one step.

A number of capability checks need to be added yet to keep users in-line.

See: #140, #139
Added `stylesheet` parameter to VIP themes.

This allows us to keep track of where the theme is installed inside
quickstart and more easily fetch information from its stylesheet at a
later date.
Added `get_theme_action_link` helper function and cleaned up query args.

Previously there were different query args depending on whether or not a
them was supposed to be installed and/or activated. Now the theme to be
processed is passed as the `vipthemehelper-action` with option `install`
and `activate` boolean args.

The `get_theme_action_link` function generates a link that when navigated
to will cause the correct action to be taken.
Using WP_List_Table in the VIP Theme Helper widget.

Looks better and is more organized.
Adding status indicators to VIP Theme Helper table.
Fixing incorrect query parameter in get_theme_action_link.
Update the SVN Credential Form for VIP Theme Helper.

Adding controls so that the user can select whether they want the theme to
be installed and/or activated.
Added a failure message to the VIPThemeHelper widget when not connected.

Now when the widget is not connected to WordPress.com it will print out a message asking the user to connect rather than printing an ugly empty table.