if no emails after sync, log user out

fixes #1472
extend wcli.{get,post} to return information about the original request if available
improve details on failures to show original request info
Remove the window.unload event in the KPI event stream.

If we do not need the event for KPI processing, this allows us to avoid making changes to WinChan - see issue #3861

issue #3794
Merge pull request #3865 from mozilla/clear-certs

Add the ability to clear certs from localStorage in the development menu
Merge pull request #3820 from seanmonstar/hotfix-1472-no-emails

if no emails after sync, log user out
Merge pull request #3862 from jrgm/loadgen-improve-error-detail

[load_gen] improve details on failures to show original request and response code and body
Merge pull request #3864 from mozilla/issue-3794-ditch-window-close

Thanks for the feedback @6a68 and @kparlante - I far prefer the "reduce the amount of code" approach here to the "add more brittle code" approach in the other PR. 

@6a68 gave the r+, @kparlante gave the "approach is good", merging. 

fixes #3794 by removing the offending event.
If the user has not yet clicked on "Yes, this is my computer", remove the cert after generating an assertion.
Update the remove email test to deal with "one time certs" when re-signing in with secondPrimaryEmail