change color_histogram showing methods with reconfigure

use dynamic reconfigure to change color_histogram degree of similarity's showing method
![config_blue](https://cloud.githubusercontent.com/assets/7259700/4200271/f5907d84-380e-11e4-8794-a97ccfea6225.png)
![config_thermo](https://cloud.githubusercontent.com/assets/7259700/4200278/0a2a5b8e-380f-11e4-8227-0dacfd529f58.png)
this picture shows changing showing method, simple-one and thermo-like-one