fix(web-server): strip scheme, host and port
docs: Add assets loading section

Add examples to loading assets like images, also loading assets using
proxy, to avoid confusion arising from need to use 'base' after URL
docs: add the troubleshooting section
and move some questions from the faq into it
Merge branch 'pr-1006' into presubmit-stable-pr-1006
Merge branch 'pr-899' into presubmit-stable-pr-899
chore: release v0.12.9
docs(ember): Add note for tying karma start to App.initialize

Tests against an ember application should not start until the
App has completed initializing.  The note and suggested
bootstrap method demonstrate how to deactivate karma autostart
and how to explicitly start karma at the appropirate time.

Closes #1012
Merge branch 'pr-1017' into presubmit-stable-pr-1017
Merge branch 'pr-1029' into presubmit-stable-pr-1029