The KOReader plugin's update check response provides the server version,
which already contains a leading "v". The update and plugin popups in
the KOReader plugin format the version with an explicit "v" prefix,
resulting in a "vv" typo (e.g. "vv1.2.0").
Strip the leading "v" from the server version in the updater script
if present to ensure it is displayed with a single "v" prefix.
Closes#644
neon
568bf9dd6f