* Adds a new metadata helper and methods to PostPresenter to have metas on post pages.
* Adds tests to post controller to check correctness of metas
* Add methods to PersonPresenter to have metas on profile pages
* Correct meta data helper test
* Update PersonPresenter, add test to PeopleController
* Creates TagPresenter. Display tag metas on tag index page
* Updata meta data helper spec
* Not displaying bio as the description meta on profile page for now. Privacy concerns to be cleared.
* Set meta info as hashes in presenters
* Move original hardcoded metas info to config/defaults.yml
* metas_tags include by default the general metas, update views
* Update code style, clean views
* Renames TagPresenter StreamTagPresenter, updates TagController spec
* Add a default_metas entry to diaspora.yml.example
* Align metas hash in presenters, refactor meta data helper
* Use bio as description meta if user has a public profile
* Rename StreamTagPresenter to TagStreamPresenter
