Ignore unity import auto-generated meta

[ShortDevelopment]

Reasons for making this change: When you import a local *.unitypackage file into Unity, the editor might save a copy of the imported package file next to the extracted content.

Unity creates a <filename>.meta file for every file. As *.unitypackage is already ignored in the template, only the *.unitypackage.meta file gets checked into version control.

If user A imports the package, his unity instance creates the meta file, and it gets committed. The unity instance of user B sees only the *.meta file and automatically deletes it. User A gets a commit with the *.meta deleted, so his Unity recreates the file.

This causes an infinite cycle of creation and deletion.