finish refactor to use Api.apiParsePost() and Api.apiFormPost() when invoking POST

* Fixes #468
* N.B. i didn't bother to refactor Login.js, because its usage is still pretty disjoint from everything else, so i assert that it's not worth the time until we have changes we want to make to login/logout behavior
* Jenkins: http://jenkins.buttonweavers.com:8080/job/buttonmen-cgolubi1/99/