Fix the damn build button

It needs to query the server to determine whether a new version is
available to build.
clean up comments and console.logs()
Verify latest release on client is accurate

before building a new release
dim deploy btn while building
Merge remote-tracking branch 'origin/master' into test

Conflicts:
	corehq/apps/app_manager/static/app_manager/js/releases.js
	corehq/apps/app_manager/templates/app_manager/releases.html
Merge remote-tracking branch 'origin/master' into test

Conflicts:
	corehq/apps/app_manager/static/app_manager/js/releases.js
	corehq/apps/app_manager/templates/app_manager/releases.html
Properly handle an empty build list
Dim the `make new version` button while querying
Merge branch 'build_button' into test

Conflicts:
	corehq/apps/app_manager/templates/app_manager/releases.html
Change the wording in an alert
Merge pull request #1658 from dimagi/build_button

Build button asynchronous operation