Merge pull request #67 from therealdjryan/master

Just tried this, and it works - thanks @therealdjryan!

src/common/aria2_downloader.py

@@ -64,7 +64,9 @@ def start(self, blocking=False):
         if self.hash_type:
             checksum_opts = ['-V']
             checksum_opt = '{}={}'.format(self.hash_type, self.hash_value)
-        port = 5900
+
+        port = self.find_available_port()
+
         l1 = [
             _aria2_path,
             '-d', self.dest,
@@ -106,6 +108,15 @@ def start(self, blocking=False):
                 self.failed = True
                 self.failure = e
 
+    def find_available_port(self):
+        import socket
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.bind(("", 0))
+        s.listen(1)
+        port = s.getsockname()[1]
+        s.close()
+        return port
+
     def getAriaStatus(self):
         self.process.poll()
         if not self.process.returncode: