Feature/improve textareas

Copy of https://github.com/unikent/programmes-plant/pull/182 forked off develop

After playing around with and giving up on a number of the lighter weight html5 editors, I've ended up going for ckeditor. Although it doesn't currently look as pretty, it seems to be quite a bit more stable in terms of ensuring everything works as expected (especially when pasting is involved).

may still need quite a bit of tweaking to get it to look/work exactly how we want.