Added delta hyperbolicity code along with corresponding gtests.
The gtests cover connected and disconnected graphs.
Currently, requires omp to compile and run.
Merge remote branch 'upstream/master'
Merge branch 'master' into features

Conflicts:
	lib_graphd/inc/GraphProperties.h
	lib_graphd/src/GraphProperties.cpp
Added powerlaw and delta hyperbolicity to graph_stats.cpp
Merge remote branch 'upstream/master' into merge_test

Conflicts:
	util/src/graph_stats.cpp
Fixing boost_graph not wrapped in ifdef and moving betweenness variable outside ifdef region in header.
Fixing allocation of array with variable size by replacing with vector and resize/dynamic allocation
fixes for building with metis and no openmp
Merge branch 'fix-kcores'
Merge pull request #27 from jlothian/fix-kcores

fixes for building with metis and no openmp
Merge branch 'master' of github.com:jlothian/INDDGO-survey
Merging upstream
Fixing METIS+ no OpenMP compilation
Merging powerlaw and delta hyperbolicity code from Schrock
Fix compile issue in graph_stats
Added some conditional defines to enable gtest and boost to co-exist in relative peace and tranquility