Workaround for proxy problems on Windows (Qt bug?).

Reviewed-by: kh1
(cherry picked from commit f3ac8e43)

Workaround for proxy problems on Windows (Qt bug?).

Reviewed-by: kh1

Reviewed-by: ck

This reverts commit 4c29c61a.

The device configuration widget is now the only place the user
ever has to specify ports.

Currently hidden.

This makes us more independent of the developer PC's firewall setting.

Reviewed-by: kh1

Task-number: QTCREATORBUG-1460

Reviewed-by: kh1

It does not conceptually belong there, and several people have
asked for an interface to use the functionality in their own
plugins.

Task-number: QTCREATORBUG-1204
Reviewed-by: kh1

Task-number: QTCREATORBUG-1074
Reviewed-by: kh1

Reviewed-by: kh1

This user now also resides under /home on the device.

This will replace the current ssh-via-QProcess approach, which
has severe drawbacks.

Most attributes have moved into the settings page.