Fix/bash env test

[msutter]

Using the plugin in some docker images produce an 'unbound variable' error by pushing charts to the nexus repository.

You can reproduce this issue by using the 'devth/helm' docker image.

This pull request makes the following changes:

• Adapt the bash 'if' checks on env vars with the :- notation to set a default value empty string
  (http://wiki.bash-hackers.org/syntax/pe#use_a_default_value)
• Move the setting of the AUTH env var to include the case were passing user/pw to the push command
• Add a 1.0.0 version as defined in semantic versioning

[sonatypecla]

Thanks for the contribution! Before we can merge this, we need @msutter to sign the Sonatype Contributor License Agreement.

[DarthHater]

@dtshepherd wdyt about this one?

[dtshepherd]

Sorry @DarthHater, I've just been absolutely slammed at work lately. This PR looks good and I see an overlapping PR #2. I like this one more because it keeps the set -u, so maybe just add the rename of USERNAME to REPO_USERNAME, so the script doesn't create a conflict with Ubuntu?

[dtshepherd]

@msutter Did you want to make the change I suggested above so we can get this merged? (sorry for being slow to respond, slammed in my day job...)

[marcoreni]

@dtshepherd @DarthHater any updates on this? After the changes suggested in #1 (comment) it should be straightforward to merge, right?

[dtshepherd]

Yeah, should be. If I find some spare cycles this week, I can fork this change and apply my suggested fix.

[anton-johansson]

Any news here? I just upgraded my Nexus to get native Helm chart support, but I got stuck here. :)