Add the DISCLAIMER file for Apache incubator project (#28)

Partially-closes: apache/incubator-openwhisk-release#180

DISCLAIMER.txt

+Apache OpenWhisk Runtime Python is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Apache Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.

README.md

@@ -114,3 +114,7 @@ Using IntelliJ:
 -Dhttp.proxyHost=localhost
 -Dhttp.proxyPort=3128
 ```
+
+# Disclaimer
+
+Apache OpenWhisk Runtime Python is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Apache Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.