handle kpi data that contains no event stream.

* Pass errors up the stack during initialization
Add a siteName, siteLogo and backgroundColor.

fixes #85
Merge pull request #86 from mozilla/issue-80-login-loop

Fix the login loop of death.
Merge pull request #88 from mozilla/issue-87-rp-branding

Add a siteName, siteLogo and backgroundColor.
data-->datum
Merge pull request #90 from mozilla/issue-84-no-event-stream-import

Issue 84 no event stream import
Merge branch 'master' of github.com:mozilla/kpi-dashboard

Pull Shane's latest round of fixes