Added support for images from /public location

[abujeda]

Added support to use images from /public location (eg: /var/www/ood/public).

• By default, icon_tag helper prefixes image URIs with the application path, /pun/sys/dashboard. This was not allowing to use image deployed in the public Apache folder.
• This helper is used for pinned apps images and navigation items.

tile:
  title: "RStudio 400"
  icon_uri: "/public/images/rstudio_logo.png"
  border_color: "blue "
  sub_caption: |
    Custom Text Line 1
    Line 2
    Line 3

Pinned apps fixes to the image width when the custom image is wider than the tile.

┆Issue is synchronized with this Asana task by Unito

[abujeda]

Image width fix.
Before:

After: