tvheadend service addon: Version update, new tool & a build fix.

Updated: tvheadend version to 3.9.1085 (seems to be very stable).
New: tools/mkpkg/mkpkg_tvheadend
Fixed: copy .git during build. Otherwise tvheadend version will be 0.0.0~unknown.
we use https://github.com/tvheadend/tvheadend/blob/master/support/tarball to generate tarball.. this is not needed.