Do not show non-officially supported devices in description, e.g.:

* T23
* T27
* T29
* T49

There would ideally be another mean to easily differentiate between the
support level of the different models...

These are not "officially supported devices", so don't add them in the
plugin description.

Seems like it's official "code name" is VP-T49G, but we'll call it T49G.

Did no test other than plugging the phone.

When on a call and pressing on a function key, the phone now does an
attended transfer to the destination instead of a blind transfer.

Ticket #6037.

Remove xivo-snom-8.7.5.17 and xivo-snom-8.7.5.28. Both obsoleted by
xivo-snom-8.7.5.35.

Contribution from Vincent Garbay:
  http://projects.xivo.io/boards/8/topics/4254?r=4803#message-4803

The xivo-polycom-4.0.9 plugin obsolete the xivo-polycom-4.0.4 plugin.

The xivo-polycom-5.3.1 plugin obsolete the xivo-polycom-5.3.0 plugin.

Does not completly obsolete the xivo-snom-8.7.5.17 plugin since the
8.7.5.28 firmware is not available for all supported models.

Not used by XiVO, was proposed for removal in
https://github.com/xivo-pbx/xivo-provd-plugins/pull/12.

You would hit the bug only when picking certain timezone, like
Africa/Tunis.

I.e. need to add another check, since otherwise, people in XiVO 15.16
that would install new plugins without upgrading their xivo would find
themselves with no phonebook URL configured on their phones.

For all plugins which have new way of generating the phonebook URL.