Better local template handling with Windows compatability

[presidenten]

Windows users have trouble using local templates when the the previous solution only checked for slash and not backslash or path.sep. With this new approach mac, linux and windows users can also use relative paths to the template:

   vue init ./myTemplate projectName

or

   vue init ../myTemplatesFolder/myTemplate projectName

Tested on Mac osx with node 6.2.2 both from local build and globally installed build, as well as Windows 8 with node 6.7.0 from local build.

[presidenten]

Please wait with the merge, I broke the absolute path local init. Ill fix it and send a new pull request.

[presidenten]

There we go!
Now it also works with absolute paths. Sorry for the trouble.

It has now been tested on mac, linux (ubuntu), and windows.

[zigomir]

Thanks for working on this @presidenten, looks good to me.