add support for bulk adding graphgists

[jexp]

Add support for adding graphgists in bulk.

• use a CSV file or a list of gists
• take URLs and attributes from the CSV
• also parse the graphgist using grep or asciidotor for attributes (like author, title, tags)
• default or empty values if not available
• don't override existing, just add new ones

Some sources to add:

• All Entries to add https://github.com/neo4j-contrib/graphgist/wiki
• https://dl.dropboxusercontent.com/u/14493611/all_graphgists.txt
• https://docs.google.com/a/neotechnology.com/spreadsheet/ccc?key=0AqR5Rs3VdTSSdC0yV3FDenRpQ0Q4NnE2c2t2NURBMnc&usp=drive_web#gid=3