WebAlert: fix alerts in restricted collections

• Comment out the removal of child collections in collections_to_be_displayed and collections_to_be_searched (in wash_colls function in search_engine) since it is preventing searching in restricted daughter collections in cases when people asked for parent and all public daughter collections too.

• Add new test for ensuring the availability of search in restricted collections when the parent is also one of the collections to be searched.

• Add new function to the search_engine to get the normalised name of a collection (transformation from case-insensitive to case-sensitive).

• Wash the non-existing collection names from the alert query, and do the search only on existing ones; also normalise the names of collections, to case-sensitive. (fixes #529)

• In debug mode, alert notification emails are now going to CFG_SITE_ADMIN_EMAIL and not CFG_SITE_SUPPORT_EMAIL.

• In debug mode, alert will not add records to baskets anymore.