Set influence_map to return influence map filename
Set influence_map to return influence map filename

I wanted to turn the influence map into a computable networkx
or PyGraphViz object. I thought about creating a new function,
influence_map_as_graph() or something like that, which would
make the influence map and then return the graph built from the
.gv file, but I figured that this would introduce an extra
and completely unnecessary dependence for kappa.py and PySB.

So I left it that influence_map returns the filename, and then
it's trivial to get a Graphviz or networkx object as:

  import pygraphviz as pgv
  import networkx as nx

  graphviz_graph = pgv.AGraph('im_filename.gv')
  nx_graph = nx.Graph(graphviz_graph)

jmuhlich/pysb,spgarbet/pysb,neurord/pysb,spgarbet/pysb,neurord/pysb,LoLab-VU/pysb,spgarbet/pysb,d-fan/pysb,johnbachman/pysb,alubbock/pysb,LoLab-VU/pysb,pysb/pysb,alubbock/pysb-legacy,d-fan/pysb,alubbock/pysb-legacy,neurord/pysb,johnbachman/pysb,alubbock/pysb-legacy,d-fan/pysb,alubbock/pysb-legacy