Fix for output since L5.7+

Add L6 and L7 support

Typo fix

Fix namespace

Change namespace from "McMatters\DbCommands" to "McMatters\LaravelDbC…

…ommands".

Add new commands migrate:drop-single.
Add package autodiscovering feature.
Use "ConfirmableTrait" in DropTables class.
Import php functions and constants for better performance.

Fix for 5.5 version

Add ability to run migrate:single with class name instead file name

Update dependencies

Update composer.lock