Parse build meta information from one place

Continue the trend to put all build related information into one place.
Move the binary target dictionary data into release description file
and read it from there during the build.

The binary target dictionary holds information how each build slave
knows where to upload build artificats at the end of the build.

The buils slave labels are build system specific.

Change-Id: I38e44b95011ea108a2f4f1f85ae2f121faa5944b
Reviewed-by: Matti Paaso <matti.paaso@digia.com>