Merge pull request #25 from ke4/master

Merged the code from the development to the master branch
[fix #49834805] added data matrix to spin column

Also removed unneeded spin column header and footer
template and changed the placeholder variables
in the templates to relates the request JSON.
[fix #49834805] post to a uuid (label printer)
modifying the templates to handle Nil values
Merge branch '49834805_create_a_script_to_print_a_barcode_with_a_printer'