Move og_ui in to modules subdirectory

[RoySegall]

I think a lot of modules keep their sub modules in a subdirectory called modules. I think we should go in the same direction for og_ui(for now) and for the upcoming modules.

[amitaibu]

👍

[damiankloip]

Totally agree, this is how it is in the 7.x branch too. Just wondering if it can wait until #40 is done? However, git is clever, so reading with the rename might be smooth...

[MPParsley]

@amitaibu, @pfrenssen could you close this issue?

In #315 it's decided to remove the og_ui module.