Update Kobo driver to allow sending kepubs

[David Forrester]

With the creating of an output plugin to create kepubs (or Kobo epubs), there is a need to support sending kepubs to the Kobo eReaders. The KoboTouchExtendedDriver plugin already does this, but has other behaviour that might undesirable.

The only real change needed is the name of the kepubs on the ereader. The name and extension must end in ".kepub.epub". This tells the Kobo firmware to handle the books differently and open them using a different reader application.

There are two other changes in the patch:

- Fixed a silly spelling mistake in a variable name.
- While testing the change, I noticed a database update that wasn't needed for firmware versions that supports shelves. Added a test to skip this.

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every Friday.

 status fixreleased