Move settings scripts into sqlite DB

[smartin015]

This is a backend refactor that is a prelude to other work in #126 - moving away from explicitly declared scripts in settings code and instead allowing users to attach a gcode script to any event that CPQ fires from the state machine.

This PR also tests (and fixes a couple inconsistencies) with api.py handlers - namely a new GETSTATE permission and actually using RMJOB perm.

• Create new DB with Scripts and Events models
• Unit test new DB and associated queries
• Create & test migration script from octoprint settings --> new DB
• Convert script_runner.py to use DB queries instead of pulling from settings
• Fix script_runner.py unit tests
• Hook up migration script to plugin.py
• Convert driver.py to use new script_runner methods, fix unit tests
• Refactor JS to accept creating/deleting/editing scripts from the settings page
• Refactor JS to allow assigning/reordering/removing multiple scripts to events
• Properly handle reloading/discarding scripts state upon exiting settings
• Handle renaming settings script without adjusting event registration
• Fix any remaining broken / skipped python tests
• fix/implement tests for JS changes
• Exploratory testing using virtual octoprint instance