Bug 20554: (follow-up) Add local font files and add method for loading them

Bug 20554: (follow-up) Add local font files and add method for loading them

This patch adds local copies of the font files specified in the original
patch. A new JavaScript file has been added, fontfaceobserver.min.js,
which helps gracefully load font assets.

https://github.com/bramstein/fontfaceobserver

Information about the new assets has been added to the about page.

When using web fonts, there can be a delay, while the browser loads the
font files, between the time the page loads and the time the fonts
render. Font Face Observer allows us to specify a default font for the
initial page render, and then apply the web font after it has loaded.

To test, apply the patch and regenerate the OPAC css. View any page in
the OPAC and confirm that the custom font renders properly.

View the About page in the staff client and confirm that the new license
information looks correct.

Patch applies and OPAC and license look good. Looking forward to this.
Signed-off-by: Dilan Johnpullé <dilan@calyx.net.au>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>