CON-2008 | fixed wide table shadow on RTL wikias

They look like it was in the previous version → always darkened (in /skins/oasis/css/core/table.scss on [line 139](https://github.com/Wikia/app/blob/CON-2008/skins/oasis/css/core/table.scss#L139) and [line 149](https://github.com/Wikia/app/blob/CON-2008/skins/oasis/css/core/table.scss#L149)). I will revert this change as I found a fragment of a table in our mocks (2014_1002_articles_v1_spec.pdf on page 44) and it does not have any new styles applied.

But I am thinking now on sth else -- why this file (for Venus) is in the `shared` folder? What do you think about moving it somwhere else -- like into `extensions/wikia/Venus/styles/article/tables.scss`? @bognix ?