Merge pull request #12 from pvuorela/master

[systemsettings] support updating 12/24h to timed
[systemsettings] Remove AboutSettings::model()

Has been returning strange information. Remove until needed and
reimplemented properly.
[systemsettings] Remove const on string return values

Doesn't provide anything but noise.
[systemsettings] Remove manufacturer and productName from aboutsettings

Not returning proper information with Qtsystems.
[systemsettings] Add support for fetching software version in aboutsettings