Add scripts directory that is preserved during upgrade

[kizniche]

Problem: Currently user-created scripts associated with Mycodo (e.g. those created for functions/conditionals/actions) must be manually backed up and moved, and must be outside the Mycodo install directory due to upgrades only carrying over specific files that must be preserved.

Solution: Adding a directory that users can put scripts in under the Mycodo install directory will allow them to be preserved across upgrades, backed up during backups, and exported/imported when using the export/import feature, and ensures they remain associated with your Mycodo instance.