Adds a 'type' parameter to download.php, which, if equal to 'sitemap',
will serve up a sitemap file from dataroot.  The download.php links
are then used in the generation of the sitemap index.

Change-Id: I8b7af1a6820cf32542f3ae1bdfc8940c309939b0
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>

If for some reason the sitemap generator is called twice in a day, it
fails the second time while trying to overwrite the previous version.
This can be fixed by removing all sitemaps for the current day before
attempting to regenerate them.

Change-Id: I48c3ff5c99948e4c5ab93007f068f0319dfac2f8
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>

The cron process can't write to the docroot, so we'll have to write
sitemaps to dataroot and make them accessible another way.

Change-Id: If3b09f7322f59beed9eba1ac3d6f63c667909dfa
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>

When sitemap generation is disabled, we don't need to include all the
relevant libraries and log the message about disabled sitemap
generation.

Change-Id: I1f7e92f58dcb455bbfaab7745ce28e496ee7276b
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>

Bug #797035 - This code adds a date tag to the filenames
and adjusts the index generation to be based on the sitemaps
directory content.

When run on the first day of a month (or if a full
generation is forced), the sitemaps directory is emptied
beforehand.

Change-Id: I71b67b200cd5c7c1dcd10c3f6ceb7f74bf04b6ae
Signed-off-by: Darryl Hamilton <darrylh@catalyst.net.nz>

Code to generate a sitemap generation code, using the sitemaps.org
standard/protocol. The default generation is daily, with a
full generation done on the first of the month. The full
generation can also be forced by passing 'true' to the constructor.

Sitemap file(s) are placed in a 'sitemaps' directory just off
the docroot, with an index file placed in the docroot itself. If
the 'sitemaps' directory does not exist, one will be created.

More information can be found on
https://wiki.mahara.org/index.php/Developer_Area/Specifications_in_Development/Sitemaps



Change-Id: Ib28983ca1c3b5ff06a6e603f402460531b987067
Signed-off-by: Darryl Hamilton <darrylh@catalyst.net.nz>