Upgrade typescript, react, jest, & enzyme#1583

Merged

chandlerprall merged 16 commits intoelastic:masterfrom chandlerprall:typescript-v3

Feb 25, 2019

+2,423-2,418

Commits on Feb 13, 2019

upgrade to typescript v3, add it as a peerdep to enforce downstream project support
chandlerprall
committed

Commits on Feb 20, 2019

upgrade to typescript v3, add it as a peerdep to enforce downstream project support
chandlerprall
committed
Change popover positioning's align type to use undefined instead of null
chandlerprall
committed
Upgrade @types/react and @types/prop-types versions
chandlerprall
committed

Commits on Feb 22, 2019

Commits on Feb 25, 2019