Show config in a re-usable format

Config was outputted as: VAR=<plain-string>
This presents issues with multiline strings, for instance:
 ONE=something
 continued
 TWO=something not continued
This patch outputs this instead:
 ONE='something
 continued'
 TWO='something not continued'
The enclosing 's lets a parser know that the line is continued without needing to be hacky
If the config variable contains 's then the output is:
 ONE='something '\''extra'\''
 continued'
This allows easy bash re-use.