Upgraded Bootstrap and FontAwesome

New major version as using the new Bootstrap and FontAwesome versions will break old views.

• Now using Bootstrap 4.0
• Now using FontAwesome 5
• All views have been updated to use the new versions
• Also using CDNs for requirements where applicable (i.e. Bootstrap, FontAwesome and more)
• Application title configured in config/settings.php is now being used in resources/views/templates/main-layout.twig
• PHP >7.0 is now required in composer.json (was mandatory anyway, because of using Twig >2.0)

Optimizations and Fixes

• Added an "Admin Dashboard"
  • You can manage (create, update, delete) users there
  • Passwords can be reset (and will be auto-generated)
• Small optimizations regarding layouts and views
• Show errors on the web if app.debug is set to true in config/settings.php
• Fixed the ErrorHandler
• Fixed two errors in is_current_path twig extension
• Added middleware for removing trailing slashes
• Added possibility to override OldInputMiddleware: Just set $_SESSION[forget_old_input] = true in the controller function when needed
• Some code refactoring
• Also updated README, installation is now a bit more easy

Big new release

Changes

• Restructured project
• Cleaned unnecessary files
• Added useful Middleware:
  • CSRF protection
  • Form validation
  • Keeping input data between requests
  • Authenticated-/Guest-only routes
• Changed some Propel settings:
  • Models are now namespaced and go into the 'app' directory
  • Use propel generated database config (propel/generated-conf/config.php) in bootstrap/bootstrap.php instead of static/manual config (bootstrap/database.php)
  • Removed the no longer needed config file and related entries in config/settings.php). Updated classes/files that use the models to use the namespaced ones
• Updated used Twitter Bootstrap and Font-Awesome
  • Added their "raw" files for convenient modifying
• Updated README correspondingly