Power law fitting added to GraphProperties
Power Law fitting added to GraphProperties and compiles. Added a gtest, but currently doesn't work.
Power law fitting has been added as well as a gtest for it.
Need boost/math/special_functions/zeta.hpp and accompanying headers to compile.
Also, the directory holding these headers needs to be included in lib_graphd/src/Makefile
Merge branch 'features'
Merge pull request #29 from jdlschrock/master

Adding power law fitting from jdlschrock