Adding glyphs to Arabic fonts

Hi Dave et al
I've added a page on the above as you suggested, and also included an (optional) appendix on installing FF on Ubuntu 14.04.  I also added a note to README to say you need ruby-dev installed before gem install jekyll will work. 
Kevin
`I am grateful to` &rarr; `Thanks to` (better to not single-person on a collaborative guide)

Also I'd probably move the credits at the bottom eventually.