vim: variants conflict with each other

vim: variants conflict with each other

This adds conflicts between the variants,
because they provide the same files, and it should not be
possible to install them side by side. Otherwise, it might happen that
half files would be from one variant and the other half from the
other.

Also, adds provides as if you request to install ``vim`` and
``vim-full``, then the request could be satisfied even they collide,
because ``vim-full`` provides ``vim`` package.

Signed-off-by: Karel Kočí <cynerd@email.cz>
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
[add commit message]