Parameterise the version displayed in the GUI title

so that all the translations don't become out of date every time
the version number changes
Merge pull request #44 from lurch/dont-translate-version

Don't translate version number
Itended fixes for #38
Merge branch 'dev' of https://github.com/raspberrypi/noobs into dev
Fixes #38, #21 and #20. Requires rpi-firmware update.