Docs: Separate Tether out from docs.min.js

Docs: Separate Tether out from docs.min.js

We can't include it in docs.min.js because docs.min.js includes application.js,
application.js depends on bootstrap.js,
and the tooltip portion of bootstrap.js depends on Tether.

So instead, we need to load Tether separately before bootstrap.js

[skip sauce]