Minor changes that improve the app in smartphones:

- When the app loads, load via AJAX the status of any refresh feed jobs requested by the user, but do not perform any of the other actions that are performed when the user clicks on the "start" link in the sidebar. Specifically, do not hide the sidebar. We want the user to be shown the sidebar when he first loads the app, but afterwards when the user goes to the start page (because he clicks on the "start" link or because he requests a feed refresh), we want the sidebar to be hidden and the start page to be displayed.

- When the app is instructed to go the start page, the sidebar is hidden so that the start page is visible. Old behavior was toggling the current visibility of the sidebar; this worked while the only way the app could be instructed to go the start page was if the user clicked on the "start" link, which meant the sidebar was shown and the toggling hid it. Now the app also goes to the start page when a feed refresh is requested, which can happen regardless of the sidebar visibility. So we need the sidebar to be hidden inconditionally, regardless of its current state.
When setting the current feed or folder in the angularjs app, hide the sidebar instead of toggling its current visibility state.

When the only way to set the feed/folder was clicking on the sidebar links, toggling worked fine because for this to happen the sidebar had to be visible, and toggling made it hidden. However now the current feed can also be set by clicking on the feed link in a job status alert; when this happens the sidebar is hidden, and toggling it would make it shown, which is the opposite of the desired behavior. The fix is to hide it unconditionally.

The fix is only really necessary when setting the current feed, but it's also applied when setting the current folder for coherence in the code.
When setting the current feed or folder in the angularjs app, open the corresponding folder if it isn't already open.

This is necessary when the user clicks on the feed link in a job status alert. This sets the current feed to the refreshed feed, but if the feed's folder is not open in the sidebar, it is not immediately obvious that that feed has been selected.

The fix is to open automatically the folder (and close any other open folder), so that when the user clicks on the link the feed becomes automatically visible in the sidebar and it's obvious it's been selected.
The placeholder image (a spinner) displayed while images are lazy-loading has a 3px right and left margin (same as small images after lazy loading them).

This makes any text which is right after the image have a small separation from the spinner, which looks better.