fix incompatibility of flask reload and port searching (#793)

* WIP

* add --developer; fix incompatibility of --port and --debug

* put REST tests on separate ports

* PR review

server/utils/utils.py

@@ -10,10 +10,17 @@ def find_available_port(host, port=5005):
     # Takes approx 2 seconds to do a scan of 5000 ports on my laptop
     num_ports_to_try = 5000
     for port_to_try in range(port, port + num_ports_to_try):
-        with contextlib.closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
-            try:
-                s.bind((host, port_to_try))
-                return port_to_try
-            except socket.error:
-                pass
+        if is_port_available(host, port_to_try):
+            return port_to_try
     raise socket.error(errno.EADDRINUSE, f"No port in range {port} - {port + num_ports_to_try - 1} available.")
+
+
+def is_port_available(host, port):
+    is_available = False
+    with contextlib.closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
+        try:
+            s.bind((host, port))
+            is_available = True
+        except socket.error:
+            pass
+    return is_available