fix(SDP): don't separate fmtp parameter with spaces (#2034)

* fix(SDP): don't separate fmtp parameter with spaces

* adjusted tests accordingly to not expect spaces anymore

modules/sdp/SDP.js

                                 + parameter.getAttribute('value'));
                     })
                     .get()
-                    .join('; ');
+                    .join(';');
             sdp += '\r\n';
         }
 

modules/sdp/SDP.spec.js

 a=mid:audio
 a=rtcp-mux
 a=rtpmap:111 opus/48000/2
-a=fmtp:111 minptime=10; useinbandfec=1
+a=fmtp:111 minptime=10;useinbandfec=1
 a=rtcp-fb:111 transport-cc
 a=rtpmap:103 ISAC/16000
 a=rtpmap:104 ISAC/32000
 a=mid:audio
 a=rtcp-mux
 a=rtpmap:111 opus/48000/2
-a=fmtp:111 minptime=10; useinbandfec=1
+a=fmtp:111 minptime=10;useinbandfec=1
 a=rtcp-fb:111 transport-cc
 a=rtpmap:103 ISAC/16000
 a=rtpmap:104 ISAC/32000