checkbox-touch: build-me now can embed individual providers

Fixes: https://bugs.launchpad.net/checkbox-touch/+bug/1397269
Signed-off-by: Maciej Kisielewski <maciej.kisielewski@canonical.com>
checkbox-touch: documentation update

Updates to README:
Updated info about how to embed providers into click package.
Added TL;DR section.

Signed-off-by: Maciej Kisielewski <maciej.kisielewski@canonical.com>
"automatic merge of lp:~kissiel/checkbox/fix-1397269/ by tarmac [r=zkrynicki][bug=1397269][author=kissiel]"