Add strong visual indicator of dev vs. production.

I'm putting obvious bg images in the top navbar, for DEVELOPMENT (if
domain matches 'dev*') and STAGING (staging*). Production sites have the
normal appearance.
Smarter domain detection, less hideous banners.
Added hover-text and support in curator app.
Merge branch 'master' of github.com:OpenTreeOfLife/opentree into dev-domain-indicator

Conflicts:
	curator/views/layout.html
	webapp/modules/opentreewebapputil.py
	webapp/static/images/banner-dev.gif
	webapp/static/images/banner-staging.gif
	webapp/views/layout.html
Merge pull request #340 from OpenTreeOfLife/dev-domain-indicator

Dev domain indicator