HG-332 Linked images

Handle images that link to other articles.

Related Wikia/app change: https://github.com/Wikia/app/pull/5340

https://wikia-inc.atlassian.net/browse/HG-332
This is the same as https://github.com/Wikia/mercury/pull/359/files#diff-11c5a9b14f74b34a47912876084c2fbeR5
I am just wondering, if it is possible to reuse it.
The answer might be 'no', I am just wondering :)