Change colors of architecture diagrams

[raucao]

From a forum comment:

in the architecture diagrams you use the colours red and green to discern between developer- and user-managed entities, respectively. However, those two colours are the ones that are hardest to keep apart for most colour blind users, so you might want to change one of them

[raucao]

By the way, I'm also pretty bad at vector graphics, so I didn't manage to remove that odd horizontal line in the storage cylinders and fill the whole area with color. Would be great if someone could help with fixing that.

Any improvements to the graphics would be very much appreciated, not just colors and fixing the filling, of course!