Resolve issue for initial update on source build

On a "source" installation the version.txt file is not set, and there was no update mechanism.

remove version.txt from build fully and ignore future updates to file

altered update logic to check if 'no version file' exists and its a source install type
- if true provide the option to update.
Once updated the version.txt file is written and normal current v latest version checks continue

git and windows updates remain unchanged.