Popper.js now properly supports Bower

Travis 🙄

Merge pull request roots#1943 from roots/bs4-beta

Bootstrap 4 Beta, Sage 9.0.0-beta.4

Merge pull request roots#1884 from roots/beta3

Sage 9 Beta 3

Merge pull request roots#1840 from roots/8.5.1

Sage 8.5.1

Merge pull request roots#1806 from roots/beta2

Beta 2

Merge pull request roots#1795 from roots/beta1

Beta1

Merge pull request roots#1751 from roots/alpha4

Sage 9-alpha.4

Sage 8.5.0