authenticator interface added

src/main/java/org/aktin/dwh/Authenticator.java

+package org.aktin.dwh;
+
+public interface Authenticator {
+	/**
+	 * Determine whether the given user and password combination is granted
+	 * the given role.
+	 * @param user user name
+	 * @param password password
+	 * @param role role
+	 * @return true if all criteria are matched, false otherwise
+	 */
+	boolean verifyUserRole(String user, char[] password, String role);
+	
+	/**
+	 * Determine whether a given user and password combination
+	 * has admin privileges.
+	 * 
+	 * @param user user name
+	 * @param password password
+	 * @return true if the user is admin and the password is correct
+	 */
+	boolean verifyAdmin(String user, char[] password);
+}