missing error message when web api is down

if you try to set up service by selecting one of the providers in the list, or adding a new provider, and the web api is down, you get weird behavior:

• it gets stuck for a while on "downloading authentication certificates"
• then it stops and reports "not a secure provider"
• then if you select the notification and open the dashboard, it lets you try to connect but never does. the log has the error "cannot load inline certificate file". i suspect it just never go a client certificate since api is down.

changes should be:

• give an error when api is down saying the service is down
• don't let the user open the dashboard unless we really are ready to connect (provider is successfully set up, client cert downloaded, etc).

(from redmine: created on 2013-08-02, closed on 2014-06-20)