Add start for ESO archive

[DanielAndreasen]

This is related to issue #1. Definitely not done, but a start. Some suggestions are welcome. Documentations for this can be found here

[jason-neal]

I was thinking...
I might be an idea to make the username just a keyword. So you don't need to specify it when just searching for data.

I know argparse has mutually exclusive flags but I am not sure about mutually inclusive.
You could make it so you only need to pass username when actually need to login.
e.g. username require when you want to --download the files.

python eso_archive.py --object Aldebaran --download --username xxxxx 

python eso_archive.py --object Aldebaran --download 
Warning: You need to supply a username to download data from the eso archive.

What do you think?

[DanielAndreasen]

I think it's a solid suggestion. Let me have a look

[jason-neal]

Also following the astroquery.eso docs you can have automatic login setup with astropy.config.

So maybe the mutually inclusive is constraint is not a good idea, in case you want to have it stored automatically.

Just have it as a keyword.

[coveralls]

Changes Unknown when pulling d324787 on eso_archive into ** on master**.

[DanielAndreasen]

Seems like this project is dead, and I want to clear out my open PRs