Tooltip extravaganza

Fleshing out tooltips just about everywhere. Things to mention:

* I haven't run the Selenium tests yet (Travis should do that) - they're not running locally for me at the moment. I also haven't updated the tests for any changes in translations

* There are several places that now rely on aliases/merging for tooltips and other translations where they should be the same across related types of objects (e.g. digital objects and their components, archival objects and resources, different note types). This probably needs a sanity check (maybe from @payten?) because I want to make sure it isn't entirely horrible to maintain.

* There are a few places where tooltips I added are not displaying (noted in YAML comments; see, for example, linked_agent.ref_tooltip, term.term_tooltip, enumeration.name_tooltip)

* I got stuck on figuring out how to have a custom tooltip (or placeholder) for notes depending on type. For example I'd like there to be different information that appears depending on whether the note type is custodhist, appraisal, etc. I'm not sure if a tooltip is the best place for this so I'd be eager to have feedback. If it's better to break that out into a new feature request that's cool too.