bitbake: toaster: set varibales on bitbake server

bitbake: toaster: set varibales on bitbake server

Set project variables using connection to bitbake server
instead of writing them to toaster configuration files.

This is a way to avoid rewriting configuration files before
and after every build, triggered by toaster UI.

(Bitbake rev: 3f77c69b867735b5d27c6ab7c62e39ac8d5cb2b5)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: brian avery <avery.brian@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>