handle implict subdirectories when unpacking with LuaZip
use correct path for is_dir check
Merge pull request #235 from siffiejoe/unzip

handle implict subdirectories when unpacking with LuaZip
filter message when deps_mode="none"

On Buildroot, we call `luarocks make --deps-mode=none --keep foo.rockspec`
So, the message about missing dependency is confusing.

```
Warning: skipping dependency checks.
...
Missing dependency for cgilua 5.1.4-1: luafilesystem >= 1.5.0
```
Merge pull request #236 from fperrad/patch-1

filter message when deps_mode="none"
remove exe wrappers, just batch files on windows
check is_lua by compiling the file
Merge pull request #237 from Tieske/no_exe_wrapper

No exe wrapper on Windows
Removed some unused variables
Merge pull request #239 from mpeterv/remove_unused_variables

Removed some unused variables