Added a server migration mode setting which will be used to prevent that LE tries to recreate certs during a server migration.

- cleaned up some javascript

Removed backup_dir_mount_cmd option from Sysstem > server config. The option has been replaced by a script /usr/local/ispconfig/server/scripts/backup_dir_mount.sh. If this script exists, is exacutable and is owned by the root user, then it will be executed upfront of the backup jobs when the option "Backup directory is a mount?" is enabled in server config settings.

- Updated Linux Distribution detection to recognize all wheezy sub versions correctly.

- Added options to use a mounted backup directory. This allows for remote backups, e.g. vis sshfs to a backup server. The backup script checks if the backup directory is mounted, and if not, tries to mount it.

Fixed: password match function blocked tabs incorrectly
Fixed: set focus on username input field threw an error if this field did not exist on a page

- Added "actions" framework in server to replace the functions provided by the core modules
- Moved system update function from remoteactins core module to software update plugin.

Network Configuration through the ISPConfig interface for debian and compatible linux distributions.