fix minor bugs

Remove unnecessary queries from login page and fix some bugs with the
new configuration values.
fix minor bugs

- add directories for import/export files to .gitignore
- add only plugin files to pluginmap
- fix highlighter in jd tables
- fix form submit for tools
fix #1120

Improve tool for database backup/import:
 - add gzip-reader
 - new classes for backup
 - new class for analyzing a json file
 - complete refactor of json importer
 - new class for results of the import
 - unittest for json import

Within this: fix minor bugs.