There can now be more than one variable be set.

Reviewed-by: kh1

Reviewed-by: ck

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

All our classes should have the Maemo prefix because we don't have
a namespace of our own.

Get rid of redundancy, add sanity check, better status reporting.

Task-number: QTCREATORBUG-1686
Reviewed-by: ck

Reviewed-by: ck

Fixes: - react on build/ run configuration changes
       - now notices environment changes, like switching Qt versions
       - start button is now only shown if we have a valid qemu runtime
       - enabled/ disabled state works properly when loading a project

Task-number: QTCREATOR-210, QTCREATORBUG-1252, QTCREATORBUG-1082
Reviewed-by: ck

Fixes: - react on build/ run configuration changes
       - now notices environment changes, like switching Qt versions
       - start button is now only shown if we have a valid qemu runtime
       - enabled/ disabled state works properly when loading a project

Task-number: QTCREATOR-210, QTCREATORBUG-1252, QTCREATORBUG-1082
Reviewed-by: ck