Updated PRAW to 2.1.6

This update fixes spamming during times when reddit is under heavy load.
Changed varchar from 10 to 7
Restructured database

Should be more efficient now. Only comment ids that are replied to are
stored in the database. The database no longer houses the comment ids of
VerseBot's comments, or the comments with invalid commands.
Changed .p file extension to .pickle

Github incorrectly recognized the .p files as OpenEdge ABL files.
Updated README with new file extensions
Updated CHANGELOG with recent changes
Fixed VerseBot info inconsistencies