Merge pull request #1 from dkarlovi/master

Sređen CURLOPT_SSL_VERIFYPEER da uključuje validaciju remote CA
Filename u underscore
Production certificate
Control SSL cert via property,
Method to run in production mode.
Update primjera
Primjer stavljanja u produkcijski mod
Update README.md
Use invoice as default xml when making request in example.
Merge remote-tracking branch 'origin/master'