Added YAML syntax highlighting

Downloaded from: https://github.com/chase/vim-ansible-yaml
Added new mapping
<F9> only opens quickfix window an sets "number"ing
Fold text improvements

includes foldstart and foldend lines
Added :DiffOrig function

...for displaying vimdiff when file is changed from outside and following
error rises:
"W11: Warning: File xxx has changed since editing started"