add ldap-search command to occ

Conflicts:
	apps/user_ldap/appinfo/register_command.php

LDAP search filter creation changes:

1. do not prepend * wildcard to search terms. Will result in faster search, but
you don't find "foobar"  when looking for "bar"
2. advanced behaviour when search string contains a space and multiple search
attributes are present. The search string is split into single words. The
resulting filter requires that each word at least appears once in any search
attribute. This is supposed to return better results in big LDAPs.

trim search string before passing it on