Add roslint. Code cleaned to pass roslint

Note:
- Most of the changes in the codes were made by using [Eclipse code formatter](http://wiki.ros.org/IDEs#Auto_Formatting) for both C++ and Python. But there were so many `lint` errors as well that weren't captured so that had to be manually modified.
- For Python files, only those that users would use are `lint`ed, mainly because there are so many files I can't handle.