Add inline references to contacts

[Nebucatnetzer]

#27
It would be nice to be able to add a in line reference to a contact in a journal entry.
Probably with markdown syntax.
However that would need markdown support in the journal first.

I met [Mon](Monica Geller) on the street and talked to her about such-and-such. Then we met [Joey](Joey Tribbiani) and the three of us had coffee

[djaiss]

Yes, this would be awesome.

[pflueg]

Thanks for the markdown support via #1202 .
Additionally i like to suggest a linking in the contact to all of the journal entries, where he or she got mentioned in.

[djaiss]

We can use https://github.com/zurb/tribute to achieve this. I'll start to work on this soon.