Make it work under MAC VIM Version 7.4.161

Converted some DOS line endings to unix to make errors at VIM startup go
away.
Correctly detect .asc and *.ad files as Asciidoc.

 - Previous version dit not detect *.asc files correctly

 - Adding detection of *.ad files as asciidoc
Optionally enable automatic line trimming on save

- Add 'let g:asciidoc_trim=1' to your .vimrc to enable automatic line
  trimming on save.