appveyor: report Lua coverage to coveralls
appveyor: report Lua coverage to coveralls

Trying to cover [1].

[1] https://coveralls.io/builds/2518132/source?filename=.%2Fsrc%2Fnpge%2Futil%2FtmpName.lua#L12

npge/lua-npge,starius/lua-npge,starius/lua-npge,starius/lua-npge,npge/lua-npge,npge/lua-npge