Remove broken code and simplify PS1

It's not like broken, but it's like "bad designed". Plus, I wasn't
even using it. It just made my .bashrc file bigger without a
reason.

Also, simplify PS1.

* No user; no host. This is probably unsafe but since I'm the only
  one using my computer and since this .bashrc is only sourced
  on my account --this is, it will fallback to Ubuntu's default
  bashrc when doing some `su`, I don't really need to watch my
  username all the day.

* No Git information, for now. It needs some fixes and planning.

* BUGFIX: PS1 wasn't showing in the title because of me not
  including specific title information on my PS1 string. Corrected.
  It actually shows user and host on title, I feel my titlebar
  empty if I only show path.

Since I'm planning on trying/switching to zsh, I'll keep my PS1
simple for now. I don't want to mess with my prompt at the moment.