[OE-core] Replacing Web in Sato with Midori

[Burton, Ross]

Hi,

As everyone who's used it can attest, Web (the optional browser in
Sato) is pretty rough.  Part of my plans about replacing Sato with a
leaner environment involves replacing it with Midori, and if there
isn't any disagreements I'll work on a submission to merge Midori into
Sato now for everyone who expects the Sato web browser to be useful.

This will involve pulling a few projects from meta-oe to oe-core:
ca-certificates, python-docutils and vala specifically (although its
possible that we can drop the vala dependency).

Ross