Fixing .gitignore (#2531)

* Update Unity.gitignore

Prevents directories: `Library`
`Temp`
`Obj`
`Build`
`Builds`
`Assets/AssetStoreTools`
from being included in the remote if the project sits in the `Assets` folder.

* removed wildcards from Unity's .gitignore

Unity.gitignore

-*/[Ll]ibrary/
-*/[Tt]emp/
-*/[Oo]bj/
-*/[Bb]uild/
-*/[Bb]uilds/
-*/Assets/AssetStoreTools*
+[Ll]ibrary/
+[Tt]emp/
+[Oo]bj/
+[Bb]uild/
+[Bb]uilds/
+Assets/AssetStoreTools*
 
 # Visual Studio 2015 cache directory
 /.vs/