Escape rather than filter SIMILAR TO metacharacters in patron crazy search

Escape rather than filter SIMILAR TO metacharacters in patron crazy search

The filtering I introduced in r19983 was overly aggressive, and included
characters that weren't actually SIMILAR TO metacharacters. Instead, escape
each character, carefully going through the list of metacharacters listed at
http://www.postgresql.org/docs/8.4/interactive/functions-matching.html

Works for email addresses like "foo.bar+baz@example.com".

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_1@20086 dcc99617-32d9-48b4-a31d-7c20da2025e4