Have an option to add newline to the end of marker

[keefetang]

I've found that using the blockinfile it doesn't add a newline to the end of the marker if it also happens to be the end of the file.

The newline acts as the eol, or the “end of line” character and it's required for POSIX.

Ideally it should automatically detects that it is the end of the then adds the character. This is especially useful for adding a block of text using this module on an empty file.