Standardizes episode filenames

A suggestion of standard for the episode filenames based in the following assumptions:
* No need to start with `episodio-xx-`, since all episodes are are already contained in a folder called episodes;
* Episodes filename starts with it's number followed by it's title;
* Enumeration starts at 1, no C/C++ indexes here;
* Adopted three digits to enumerate the episodes, foreseeing more then 99 episodes.

Remember: just a suggestion!