Replace jQuery-based tooltip API with atom.tooltips global

It still uses Bootstrap underneath the hood to save us the trouble of implementing tooltips, but the new API works with raw DOM nodes and does not require any access to jQuery. Since we're no longer exporting the version of jQuery that has the tooltip API, this is the only way to provide the tooltip facility now.
Thanks for this. I realized this morning that we 100% need it for the replace all in project find. One of the bugs I fixed recently necessitates focus on the mini editor for the command to work as expected.