Refactored such that the producer and consumer now inherit from a single
worker class that drys out producer and consumer a little, and no longer
compile the example against the boost libs.

. modifiedd:   Makefile
  . Added macro: BOOST_CC and moved the boost g++ command to it.
  . Removed the -DBOOST_TEST_DYN_LINK from the CC macro.
  . Removed the boost ldflags from the LDFLAGS macro.
  . Updated the $(OBJS) target to remove the boost flags

. modifiedd:   include/consumer.hpp
. modifiedd:   include/producer.hpp
  . Now inherits from worker.
  . Removed the mtx, c, id, and queue members
  . Updated constructors to call the super constructor

. modifiedd:   src/thread.cpp
  . Formatting changes.

. new: 	include/worker.hpp
  . New abstract class
  . Moved the mtx, c, id, and queue members from the producer/consumer into
    this class.