`package` command with `-path` specified should export tarball into that path

[isc-dchui]

When you call zpm "package" with a path specified, e.g. \foo\bar\, it exports the code into \foo\bar\ but creates the tarball at \foo\bar.tgz\. This is one directory level up from what is expected. The result should be \foo\bar\<module-name>-<version>.tgz. If such a file already exists, it should overwrite but provide a warning that overwriting has happened.

Note, this may break people's automation/workflows so is backwards incompatible.