Make namenode rpc and resourcemanager webapp port numbers configurable.

[jackgene]

The namenode RPC port (dfs.namenode.rpc-address....) is currently hardcoded to 9000, and the resourcemanager webapp port (yarn.resourcemanager.webapp.address...) hardcoded to 9032, which isn't typical, and requires users to update the port numbers in the Python scripts.

This update allows the ports to be defined in settings.py.

[jackgene]

As suggested here:
#3 (comment)

[vaxvms]

+1 There is several patches flying around about this functionality, it would be nice to get it in the base repo.

For instance, there is also #13 which as more feature (you can configure elasticsearch, namenode and resourcemanager hosts)

[danielcweeks]

Yes, this looks good.

The old ports were an artifact of EMR's port configurations, but even they have moved away from those and gone with the apache defaults.

Do you just want to change the defaults in the settings.py to be the apache defaults?

[jackgene]

Done. namenode rpc port set to 8020, resourcemanager webapp port set to 8088 by default.

[danielcweeks]

Thanks @jackgene !