Support "kpm pack" packing project root when '--wwwroot' is "."

[ChengTian]

@davidfowl , fixing a bug in kpm pack --wwwroot. If you specify . as the value of --wwwroot, kpm pack should pack the project root dir.

[davidfowl]

No I think means current directory not project dir

[ChengTian]

The definition of --wwwroot in issue #543 is:
--wwwroot is the name of the directory in the project that will become the public folder in the packed image
So the value of --wwwroot is a relative path to project dir. {ProjectDir}\. is {ProjectDir} itself, right?

[ChengTian]

@davidfowl , we do need this feature to be compatible with previous --appfolder feature, which packs the whole project directory as public app folder.

[davidfowl]