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

This is necessary in case there is no run configuration (e.g. for
library projects).

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

Reviewed-by: ck

Reviewed-by: ck

File maemorunconfiguration.cpp now contains what the name indicates.