Only create sqlite DB file if DB_CONNECTION undefined or eq sqlite

[tigattack]

This eliminates some pointless processing and a confusing log message in the output.

[SpecialAro]

Hello @tigattack, thank you for making this PR.

Have you tried to run ferdium-server without an SQLite file? By using a MYSQL server for instance?

If so, did it work? When I made the re-write of the code from the Adonis dependency upgrade I don't quite remember if I left that feature working.

[tigattack]

Yep, MySQL seems to be working fine for me. I was using it on 1.3.16 for a long time and moved to 2.0.6 earlier, where I encountered a few errors, but my guess is they are a result of some slightly funky logic rather than being specifically MySQL related. You'd know better than I, though - See #122.

[SpecialAro]

In fact, before updating the adonisjs dependency I did account for SQLITE databases, but forgot about other databases.

Instead of removing the logic of migrations in your PR I would suggest to adapt the script to fit MYSQL when the DB_CONNECTION != sqlite (for instance)