Exportdb refactor (#638)

* Working on export_db refactor

* Added exportdb command, removed logic for missing export_db, #630

* Updated tests

* updated docs

* Added --config-only, #606

* Added validation for --exportdb

* Added --info to exportdb command

* Fixed exportdb --touch-file to migrate database if needed

* Added exportdb --migrate

dev_requirements.txt

@@ -8,3 +8,4 @@ sphinx_rtd_theme
 twine
 wheel
 Sphinx
+pdbpp