Add archive and initialise functionality

[zeropingheroes]

Requested by @darabman

For recurring LAN parties using the same install of LANager, add functionality to download an archive of the previous party's data and initialise the database ready for the next party.

For each section of the database (e.g. shouts, videos, events, info etc) an admin could choose to one or both of the following:

• Download an archive of the section's data
• Reset the section's data to system defaults

[ilumos]

From old repo issue:

Create a SQL script or admin page that allows authorised users to 'initialise' the database ready for a new party. Such a script should ideally perform the following actions:

Archive all shouts Archive non-privileged users Disable (but not delete) events, perhaps marking them as invisible so commonly-used events (e.g. Food orders, award ceremonies, party open/close times) can be edited and reused (See issue #Num: #16 ) As above, but with info pages Archive video playlist and initialise 'Archiving' would usefully have the option of either dumping CSV/SQL or outright deleting the deprecated records

[zeropingheroes]

Move all events forward so first event start at specified date

[zeropingheroes]

Moved to main repository