EPS Utility: Validate and create strings for general purposes

This class can validate and create strings for general purposes. It can:

- Create a random string from characters of given lists
- Create a random key value and store it in a session variable
- Parse LDAP parameter values
- Check if a string is a valid boolean value
- Create a XML document from object variable values
- Add an header to a XML document
- Create a random directory with a given name length