This change to the template action plugin make template use the
platform's native newline_sequence for Jinja.
We also added the option `newline_sequence` to change the newline
sequence using by Jinja if you need to use another newline sequence than
the platform default.
This was previously discussed in
https://github.com/ansible/ansible/issues/16255#issuecomment-278289414
And also relates to issue #21128
This change corrects problems reported by the `yamllint` linter.
Since key duplication problems were removed in 4d48711, this commit
mainly fixes trailing spaces and extra empty lines at beginning/end of
files.
