Thus is the one I have: -http://www.morryde.com/products/69-small-extending-swivel-wall-mount?return=%2Fproduct-category%2F1-tv-mounts
It's a little pricey but I'm very happy with it.
It locks into retracted position, with a sprung latch, which is essential for camper usage.
If you need a bigger mounting pattern for the back of your tv (very unlikely with a 19" tv) they do make an adapter plate, or some bigger TV mounts.
We have a 22" TV/DVD combo mounted on there, and are thinking of possibly getting a 32" (most of which would need the adapter for larger mounting pattern) for next year if we see something good in cyber-Monday sales.
I bought it from Amazon, since with "free" prime delivery it worked out cheaper than alternatives, but you might be lucky at finding it cheaper elsewhere
Here are a couple of photos of the bracket from my misc mods album: -