added namespace config to edit screen

[georgekaz]

As per #70 (comment)
and vmware-archive/kubeless#1015 (comment)

1. I've added a namespace option to the editor screen (src/components/Func/FuncParams.js)
2. Changed the default namespace from "default" to "kubeless" to match the kubeless cli behaviour (src/utils/EntityHelper.js)
3. Probably pointlessly fixed the Dockerfile-prod. I don't know why it was there but it didn't build. Now it does.

No additional tests added but I've built and tested the image and the results are as expected.

Please consider this PR in lieu of that fact several people have requested this feature. Thanks

[georgekaz]

@andresmgot would you be able to review this please? Thanks

[andresmgot]

Thanks for the contribution @georgekaz !

[georgekaz]

thanks for merging @andresmgot . Could we update the creds on circleci so that the docker image can be updated please? The build is failing because it's unable to push the updated image. https://circleci.com/gh/kubeless/kubeless-ui/150

[andresmgot]

thanks for the heads up! I have updated those credentials, the image should be published now.