Issue #1691: Fixed a minor conda env bug in Makefile

[jlatone]

Summary

Made the existence test for qiskitenv case-insensitive and the naming of a new Qiskitenv consistent with the documentation (from QISKitenv to Qiskitenv).

Details and comments

See #1691 for details.

[CLAassistant]

All committers have signed the CLA.

[jaygambetta]

@Latone can you sign the CLA.

[jlatone]

@Latone can you sign the CLA.

I did, several times, not sure why it's not recognized (see image below for verification).

[jaygambetta]

it could be because jaxo added some commits.

[jlatone]

My .gitconfig was pointing to my personal github id not my IBM one at the time I pushed it back to my fork and I didn't notice until I saw the comment thumbnail on the pull...but I am an IBMer and did sign the BCG and I would think that should cover my minor contribution for now. :)

[diego-plan9]

Seems the CLA was sorted - thanks @jlatone ! For the record, the make env command is a bit stale and not currently referenced in the docs, as it is more flexible to just allow the developer to setup their environment via the tool and particularities of their choosing. Nevertheless, it's a neat fix for reducing the amount of nuisances - thanks!