[#61670334] top-cited parameter for cogitation networks

added helper functions to networks.papers:
* citation_count
* top_cited
* top_parents
minor
pylint config file
minor
Merge branch 'python' of https://github.com/diging/tethne into python

Conflicts:
	.DS_Store
Merge branch 'python' into ramki

Conflicts:
	.DS_Store