Changes:
- Fixed #335
- Fixed #339
- Added a way to rename repositories #246
- Added a way to disable access to tasks and hosts for a user
- Added a warning in repos list when a snapshot task failed
- Added periodic maintenance operations on hosts databases (optimize, repair, analyze)
- Improved the repository browsing experience (loading of large repositories, file viewer for text files)
- Code refactoring and cleanup, typo fixes
- Various UI fixes and improvements