Fix header flag

[juanjoDiaz]

I realized of a couple things from my previous PR and am fixing it with the PR.

• The noHeaders option worked as headers i.e. it set the headers when set to true. So makes sense to rename it.
• The CLI flag --no-headers is a convention from commander. Any flag preceded by --no set's it's value to false if present, i.e. --no-headers actually sets headers = false

[coveralls]

Coverage remained the same at 100.0% when pulling ab96dc9 on juanjoDiaz:bugfix/fix_headers_option into 9c861ed on zemirco:master.

[knownasilya]

I think we want a header by default, so we'd want the noHeader behavior.

[juanjoDiaz]

The header is still by default. The only thing that's changed is the parameter name.

Before noHeader = true created header and noHeader = false not. That's the oposite of what I would expect.

With this PR header = true created header and header = false not. Which makes more sense to me.

Wdyt?

[knownasilya]

Ah yes, that makes sense.