Refactor existing commands under a "files" sub command structure.

Organize the existing parse form file, read and insert in cassandra from file, and related "file" manipulations and commands under a sub command such as shown below.

`twitz file parse` Read out the contents and print to console.
`twitz file parse -f filename.txt` Read out and export contents parsed from file to another file with the passed in -f parameter name.
`twitz file cassie` Takes accounts and writes/inserts them into the configured Apache Cassandra database.

This should act as a parent issue with sub-issues created for working through adding individual ideas of this feature.