Set license under Mono/Linux

In some cases under Mono/Linux when license is set from relative path unexpected exceptions are raised.

Under Mono/Linux use one of the following ways to set the license:

1. Set license with absolute path e.g

   license.SetLicense("/home/<USERNAME>/conversion-sample-src/GroupDocs.Conversion.NET.lic");
   

2. Provide license stream loaded from the license file e.g.

   using(var licenseStream = new FileStream("GroupDocs.Conversion.NET.lic", FileMode.Open)) {
   
       license.SetLicense(licenseStream);
          
   }