Improving hidden files handling & new option to ignore VCS files

Added a new option to ignore vcs files and directories. This is useful when you want to search for hidden files but don't want to see the version control files or when version control files are not hidden (e.g. CVS).

Some improvements to hidden files handling. For directories including lots of hidden files (such as a svn workspace), this will decrease considerably the amount of iterations.
Also changed the logic used to exclude hidden files to avoid problems when the target directory is a hidden directory (e.g 'ffind ~/.gnome2 key' wouldn't return anything)