v2.0.0-alpha.3

While this is an alpha release, new servers should use this rather than an older "stable" version.

This release addresses a bunch of crashes introduced in the 2.0.0-alpha.2 release.

Features:

• Add RECAPTCHA_KEY env variable to configure ReCaptcha verification at signup with the
  included executable.

Bugfixes:

• Fix crash due to different playlist item object shape.
• Fix crash when a user role has no locale string.
• Add an error boundary to overlays so they do not crash the whole app.
• Accept both UNIX and ISO timestamp formats for booth.startTime. This makes the client work
  with üWave Core 0.5.0-alpha.5, which returns an unexpected value here.