Update schema for oracle compatibility issue

This PR changes some "page" and "site" fields from "text" to "string(4000)"  because oracle doesn't support where conditions on CLOB (text equivalent). It requires the use of a Oracle function to convert the clob into a string of 4000 characters which then works the same way as a varchar2(4000).

This fix also works on MySQL 5.0.3+ since it supports varchar fields up to 65535 characters.

PS: I made some style updates on the xml files too