Makefile rebar reference in ubuntu

[dominikb1888]

I could only make this Makefile work replacing all variable references to @$(REBAR) with the direct call "./rebar". Using Ubuntu 12.04.

https://github.com/OJ/csd/blob/Part4-20120215/Makefile

[OJ]

I had this problem as well. I shall get this sorted out when I finalise the series.