New icons to resize/design for blocks

Here are some icons that require some work (follow up of MDL-36323).

To edit:

• i/navigationitem should be 16x16
• i/info should be 16x16 and match current layout (under a quiz in the nav block)
• i/item should be 16x16 (further down under a quiz in the nav block)
• i/course should match current layout (16x16) (in courses block)
• i/rss should match current layout (16x16) (Home ► My profile ► Blogs ► View all of my entries)

New icons:

• i/rolesm which should be a proper resize of i/roles to 16x16 (Settings > Switch role to...)
• f/html to match the other f/html icons in 16x16 (would fix MDL-36446) (Activity block on front page, with a resource added in the front page)