Add post on Xen/ARM

[amirmc]

Replaces #187
Now with more atomic commits and fewer mistakes!

(line breaks make it easier to comment on the diff using GitHub's interface)

One of the posts for mirage/mirage#257

[avsm]

merge conflict on this one

[talex5]

Also, don't forget to merge this first:

amirmc#2

[amirmc]

Merged. Y'all already have push access to my repo (FYI).

Dunno why GitHub isn't sending me emails about PRs to my fork. I nearly missed your last one too.

[amirmc]

Please merge with caution as my git-fu is weak with respect to merge conflicts. What I did here is fetch and merge into my master branch and then merge that into my arm-blog branch. Following this, I made the relevant update to src/data.ml (which is the cause of the conflict).

The final commit adds a placeholder for the final release announcement so that it just has to be uncommented and edited, rather than added as new.

[talex5]

If you get a merge conflict, you should be able to run git mergetool and sort it out in a nice GUI (on Linux anyway; I assume something similar happens on OS X).

[amirmc]

Yup, that's what I did (and do). I just get paranoid because a bunch of other commits from master find their way in and then I think that as soon as I push to my fork, I'll screw up a bunch of other stuff.

This is lizard brain in full effect as I can see that the diff of files here is still as I intended. :)