Ctags: better file name defaults

Inspiration taken from http://blog.stwrt.ca/2012/10/31/vim-ctags

Signed-off-by: Dominique Rose-Rosette <drose-rosette@af83.com>
CSS: improve keyword detection

Taken from http://www.stefanwienert.net/blog/2012/02/29/vim-sane-and-fast-auto-completion-with-ctags/

Signed-off-by: Dominique Rose-Rosette <drose-rosette@af83.com>