A100, build graph based on Past Companies

See Dec 13 2013 email with Cameron for the intput data.

Input file is `.xlsx`, in excel, save as->`csv`, deliminate with Tab key.

Wrote a [perl script] (https://github.com/XiaoxiaoLi/MeerkatFacets/blob/master/A100_csv_to_graphml.pl) to convert that into `.graphml`. A node is a company, an edge is formed when a person has worked in both of these companies in the 'Past Companies' column.