Create Troubleshoot.rst (#86)

Add some guidelines due to continuous _Doesn't work for me_ issues being logged

Troubleshoot.rst

@@ -0,0 +1,65 @@
+Troubleshooting guidelines
+==========================
+
+In case of problems using ``sshtunnel`` and prior to logging an issue, please
+consider following the next steps to debug where your problem may come from.
+
+- Check if you're running the latest version (`PYPI`_ package may not be
+  updated)
+- Double-check connectivity to SSH gateway/bastion host using `paramiko`_
+
+An example of an SSH connectivity test using `paramiko`_ authenticating with
+username and password follows::
+
+    import paramiko
+    client = paramiko.SSHClient()
+    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
+    client.connect(IP_ADDRESS_OR_HOSTNAME,
+                   username=USERNAME,
+                   password=PASSWORD,
+                   allow_agent=False,
+                   look_for_keys=False
+                   timeout=5.0)
+
+
+While troubleshooting, implicitly set the local bind address and enable verbose
+logging as follows::
+
+    import sshtunnel
+
+    sshtunnel.SSH_TIMEOUT = sshtunnel.TUNNEL_TIMEOUT = 5.0
+
+    server = sshtunnel.open_tunnel(
+        IP_ADDRESS_OR_HOSTNAME,
+        ssh_username=USERNAME,
+        ssh_password=PASSWORD,
+        remote_bind_address=(REMOTE_BIND_IP, REMOTE_BIND_PORT),
+        local_bind_address=('127.0.0.1', LOCAL_BIND_PORT),
+        debug_level='TRACE',
+    )
+
+    server.start()
+    print(server.local_bind_port)  # show assigned local port
+    server.stop()
+
+Check if you've permission to listen at ``LOCAL_BIND_PORT``::
+
+    import socket
+
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s.bind(('0.0.0.0', LOCAL_BIND_PORT))
+    s.listen(1)
+    s.close()
+
+
+Additional notes
+----------------
+
+- In general, try to use wrapper (``open_tunnel()``)
+- The context manager (``with`` statement) handles opening and closing of tunnels and underlying SSH transports
+- Deprecated parameters/arguments may be deleted in future releases, thus it's recommended not to use them unless necessary
+
+
+
+.. _PYPI: https://pypi.python.org/pypi/sshtunnel
+.. _paramiko: http://www.paramiko.org/