eliminate self-edges, compute nv & replication factor
rename 'Graphlab::Graph' -> 'Grappa::GraphlabGraph'
implement forall(masters(g),...)
add forall(ghosts(g),...) and forall(g,...)
starting to do new Synchronous Graphlab engine
rename ghosts -> mirrors (to match Graphlab's terminology)
add pointers from edges to local verts, compute total in/out and keep in mirrors
forall(g,[](Edge&){...}) for GraphlabGraph
array_str: do in single line if it's short enough
implement rest of sync engine, add 'on_mirrors_async', MasterInfo