drop dl_instr dep that we have not used in forever...
pull from develop branch of dl_core.
broken sys.config file with a bunch of old comments.  messy.
drop the references to gen_leader which we do not depend on.
copied all dl_core files to local src subdirectory
move deps handling to this rebar config
clean up atoms for props
whoops, typo in export directive.  missed a comma.
stupid copy/paste error for do_write/3
merged.
moved all of these files to rel subdirectory for release building.
moved release -> rel
this is what i get for forgetting to use git mv instead of just mv
moved src folder to apps/dl_core to make r15 happy
using apps and deps layout for r15 compatibility.
use apps and deps layout
new layout means new gitignore entries.