HTTP Status 503 - The requested service () is not currently available

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <context-param>
        <param-name>org.ajax4jsf.SKIN</param-name>
        <param-value>blueSky</param-value>
    </context-param>
    <filter>
        <display-name>Ajax4jsf Filter</display-name>
        <filter-name>ajax4jsf</filter-name>
        <filter-class>org.ajax4jsf.Filter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>ajax4jsf</filter-name>
        <servlet-name>Faces Servlet</servlet-name>
        <dispatcher>REQUEST</dispatcher>
        <dispatcher>FORWARD</dispatcher>
        <dispatcher>INCLUDE</dispatcher>
    </filter-mapping>
    <!-- JavaServer Faces -->
    <context-param>
        <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
        <param-value>server</param-value>
    </context-param>
    <context-param>
        <param-name>javax.faces.CONFIG_FILES</param-name>
        <param-value>/WEB-INF/faces-config.xml</param-value>
    </context-param>
    <context-param>
        <param-name>com.sun.faces.validateXml</param-name>
        <param-value>true</param-value>
    </context-param>
    <listener>
        <listener-class>com.sun.faces.config.ConfigureListener</listener-class>
    </listener>    

    <!-- Faces Servlet -->
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>    
<!-- Faces Servlet Mapping -->
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>teste.jsf</welcome-file>
    </welcome-file-list>
</web-app>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost/sismatriculas</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.password"></property>
    <property name="hibernate.show_sql">true</property>
    <property name="hibernate.format_sql">true</property>
    
    <mapping class="entidades.Aluno"/>
    <mapping class="entidades.Curso"/>
    <mapping class="entidades.Matricula"/>
  </session-factory>
</hibernate-configuration>