Making a simpler test pack

We now have only source.id files and data.id data.
adding nodes to graph
adding edges to graph
adding edges to graphi and bug fix
adding edges to graph smaller set
adding edges to graph smaller setand bug fix
read data_list from file, verify input, output directories.
improve comments
adding a ipython notebook demo
adding a ipython notebook demo
add input and output content
Merge branch 'features/no-data-list' of https://github.com/yrahan/docgraph into features/no-data-list
removing old notebook
update notebook
update notebook
Merge branch 'features/no-data-list' of https://github.com/yrahan/docgraph into features/no-data-list