install ipython and readline on mac

ipython is a powerful interactive shell for python. With it, we can tak advantage of python programming language in our daily works.
One of ipython's power is its tab-completion feature that needs readline to work. On mac system, it lacks this library due to license issue. There is a proprietary version of readline in mac, but it doesn't work with ipython.
To install them on mac system, we can simply use easy_install utility, like this:

sudo easy_install ipython readline