Move more import code to the server

https://github.com/GNS3/gns3-gui/issues/1156

tests/handlers/api/test_project.py

@@ -306,12 +306,12 @@ def test_export(server, tmpdir, loop, project):
             assert content == b"hello"
 
 
-def test_import(server, tmpdir, loop):
+def test_import(server, tmpdir, loop, project):
 
     with zipfile.ZipFile(str(tmpdir / "test.zip"), 'w') as myzip:
         myzip.writestr("demo", b"hello")
 
-    project_id = str(uuid.uuid4())
+    project_id = project.id
 
     with open(str(tmpdir / "test.zip"), "rb") as f:
         response = server.post("/projects/{project_id}/import".format(project_id=project_id), body=f.read(), raw=True)