Bug 5755: Syspref to control facets truncation

Bug 5755: Syspref to control facets truncation

On OPAC/staff result page facets are truncated to 20 characters. On some OPAC
layout, it's not enough. A new syspref FacetLabelTruncationLength defines the
length to cut facets if necessary.

This patch add the syspref to searching.pref and add it to syspref various
language default values loaded into DB during installation process. It's not
necessary to update DB since length is fixed to 20 (as before) when this
syspref isn't defined in systemprefercences table.

Rebased to last HEAD: 2011.03.18

[Documentation] FacetLabelTruncationLength syspref in Searching tab

[3.2] It doesn't apply.

Signed-off-by: Nicole C. Engard <nengard@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>