Added site base URL configuration parameter.

Added a site base URL configuration parameter (to both the
settings page and the purge task). Cleaned up the purge
task code.`

Added URI identifier to MODS export.
Changed order of MODS export repository fields.
Changed MODS bulk export so children export.

Changed the query for information object so if an export's format is
MODS, and the current level only option isn't flagged, child
descriptions are exported in addition to top-level descriptions.

Removed typo in MOD XML template and changed template so publication status
doesn't get shown in title of parents/children.
Added XML tidying to bulk export.
Added display of total descriptions exported.
Fixed issues with MODS export of digital objects.

Fixed issues with digital object paths in MODS export.
Fixed issue with CLI bulk export breaking perms.

Fixed an issue with the CLI bulk export that caused permissions
not to work.
Fixed issue with EAD export digital object URLs.
Fix for repository name in MODS export.

Fix provided by Tim Hutchinson.
Support non-clean URLs in MODS/EAD export.

Made the URLs exported by the MODS and EAD export work if clean URLs
aren't enabled.