Cartpole error

#### Issue Description
I am running Cartpole example but troubled with a problem and I have run rhe gym_http_server.py.

十月 10, 2019 11:13:36 上午 org.apache.http.impl.execchain.RetryExec execute
信息: I/O exception (java.net.BindException) caught when processing request to {}->http://127.0.0.1:5000: Address already in use: connect
十月 10, 2019 11:13:36 上午 org.apache.http.impl.execchain.RetryExec execute
信息: Retrying request to {}->http://127.0.0.1:5000
十月 10, 2019 11:13:36 上午 org.apache.http.impl.execchain.RetryExec execute
信息: I/O exception (java.net.BindException) caught when processing request to {}->http://127.0.0.1:5000: Address already in use: connect
十月 10, 2019 11:13:36 上午 org.apache.http.impl.execchain.RetryExec execute
信息: Retrying request to {}->http://127.0.0.1:5000
十月 10, 2019 11:13:36 上午 org.apache.http.impl.execchain.RetryExec execute
信息: I/O exception (java.net.BindException) caught when processing request to {}->http://127.0.0.1:5000: Address already in use: connect
十月 10, 2019 11:13:36 上午 org.apache.http.impl.execchain.RetryExec execute
信息: Retrying request to {}->http://127.0.0.1:5000

#### Version Information

Please indicate relevant versions, including, if relevant:

* DeepLearning4j Examples Parent 1.0.0-beta5

#### Contributing

If you'd like to help us fix the issue by contributing some code, but would
like guidance or help in doing so, please mention it!