Add Irmin intro blog post
Fix remarks from @dbuenzli @bendiken and @mor1

Thanks!!!
my edits to irmin post
adjust date
Add Xen/ARM blog post
line breaks

Nothing but line breaks, I promise!
add cubieboard2 pic to arm post
fixes for pipe table and style of code segments

Table is taken from
https://github.com/talex5/mirage-www/commit/5f2496767d0df8931852088dd6efc21cdb01439a
minor changes

Change refs to Mirage to be of the form 'Mirage v1'
add post to site
Updated instructions for latest mirage-xen-minios