Device support: Make IDevice::executeAction non-const.

Presumably this function is currently const because no current
implementation actually changes device properties, but there
is no reason why that should not be allowed.

Change-Id: I80e4355be70e40bca9df5e1287a1d1d3f60c6534
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Qnx: Fixing BarDescriptorEditor to prevent loosing syntax highlighting

Task-Number: QTCREATORBUG-10039

Change-Id: I8a6b80d18da1be0697bd8aaceb5d8670105a8f49
Reviewed-by: Mehdi Fekari <mfekari@blackberry.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: David Kaspar <dkaspar@blackberry.com>