[Tests] Increase file descriptor limit

Increase the file descriptor limit to avoid 'Too many files open'
error when running tests.

deluge/tests/__init__.py

@@ -0,0 +1,13 @@
+# Increase open file descriptor limit to allow tests to run
+# without getting error: what():  epoll: Too many open files
+from __future__ import print_function
+
+try:
+    import resource
+except ImportError:  # Does not exist on Windows
+    pass
+else:
+    try:
+        resource.setrlimit(resource.RLIMIT_NOFILE, (65536, 65536))
+    except (ValueError, resource.error) as ex:
+        print("Failed to raise file descriptor limit:", ex)