added the missing steps to print a label

- choose a template,
- fill in the template, header and footer
- print the filled label
correct the TODO
removed debugger
Fixed the failing specs
returning correct user_input after an invalid value given
changed message printing to the screen
In case of connection refused ask the rootURL again
added possibility to choose another template
fix template selection
fix message printing at the end
Added how to use the app to the readme
Reformatting readme
lab printer usage
Reformatting
[#59649108] print more labels in one print process
bump the version to 0.2.0
added a script to run the application

also checks the gem dependencies and installs them
if required
formatting README
manually merged
add mandatory field check