Book: Learning ROS for Robotics Programming, 2nd Edn; Chapter 7- pr2 desctiption

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Hello; I am studying the book written for beginners. I was trying to simulate the code give in the Chapter 7 tutorials. When I started running the complete code given in the tutorial of that chapter i.e. robot with gripper (which is described in the book from page 276 - 280), I got this error.

ERROR: Model Parsing the xml failed

Digging deeper into it, I found out that error occurs in the following block

   <joint name="left_gripper_joint" type="revolute">
    <paretn link="arm_2"/>
    <child link="left_gripper"/>  
    <axis xyz="0 0 1" />
    <origin rpy="0 -1.57 0" xyz="0.06 0.0 0.04"/>
    <limit effot="1000.0" lower="0.0" upper="0.548" velocity="0.5"/>
 </joint>

<link name="left_gripper">
    <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
            <mesh filename="//pr2_description/meshes/gripper_v0/l_finger.dae"/>
        </geometry>
    </visual>
    <collision>
        <geometry>
            <box size="0.1 0.1 0.1"/>
        </geometry>
    </collision>
    <inertial>
        <mass value="1"/>
        <inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0" izz="1.0"/>
    </inertial>            
</link>

Seeing the error and block, I found the line //pr2_description/meshes/gripper_v0/l_finger.dae" suspicious. I tried to figure out this problem by reading the blogs for its installation such as this in which the method is provided for the installation for hydro. As, I am using ROS-jade under ubuntu 15.04 so I changed the command into this

$ sudo apt-get install ros-jade-pr2-desktop

but I got this message.

E: Unable to locate package ros-jade-pr2-desktop

I also read from the answers that it is under development (on the date April 2014) for hydro and someone recommended to wait for 2-3 months. Please, help me out in figuring out this problem from the book. Thanks in advance.