add color information to when users select point cloud

Selecting pointcloud date in rviz using select panel button (http://wiki.ros.org/rviz/UserGuide#Select_.28Keyboard_shortcut:_s.29), shows "selection" panel that listed all points which I selected. These data contains, name, position vector and color, but all color information is black. This patch is workaround for this issue and I checked http://wiki.ros.org/rviz/DisplayTypes/PointCloud page to use reinterpret_case for convert float data to Uint data.

```
0.0.2 RGB
Valid channel names: rgb (1 channel), r, g, b (3 channel)

RGB only affects the color of the point.

There are two ways to specify RGB:

3 channels, named "r", "g", and "b", with floating point values between 0 and 1.
1 channel, with the float in the channel reinterpreted as 3 single-byte values with ranges from 0 to 255. 0xff0000 is red, 0xff00 is green, 0xff is blue.
In C++, int rgb = 0xff0000; float float_rgb = *reinterpret_cast<float*>(&rgb); 
In Python,  float_rgb = struct.unpack('f', struct.pack('i', 0xff0000))[0]
```