Added Confirmation of Deletions, Python3.x Compat.

User must now confirm that they want to prune documents in a database,
else the script aborts. Added Python 3.x Compatibility for raw_input()
which does not exist in Python 3.x.
databaseTools.py -d/-u Accepts command line URL

-d and -u subroutines now accept and parse command line URL, which
negates the need for further interaction with script.
Updated help() subroutine and README to reflect changes.
User can specify which extensions dbTools uses

databaseTools.py -u can now ignore all files that do not have a
specified extension, i.e. .json. Works with command line URL option or
without. Example Usage: python databaseTools.py -u .json
will ignore all non .json files in directory.
Updated README to reflect changes.