Add ability to set labels on image push

[old-ocean-creature]

Add ability to set labels on image push

[vmwclabot]

@old-ocean-creature, you must sign our contributor license agreement before your changes are merged. Click here to sign the agreement. If you are a VMware employee, read this for further instruction.

[old-ocean-creature]

fixes #153

[joaopapereira]

Hey
Thanks for putting together this PR.
Looks like some tests are failing, do you mind taking a look to see what is happening.

Also not sure if it would make more sense for it to be called --label singular since you would have to provide the --label flag per label you want to add.
Another nice to have is for this to be provided with the ability to add labels to the bundles as well.
And to top it off, if you could also add some tests to ensure that the labels are being added correctly that would be awesome.

Let me know if you need help with any of the above comments

[vmwclabot]

@old-ocean-creature, VMware has approved your signed contributor license agreement.

[phenixblue]

@joaopapereira I believe this can be closed now since #552 was merged

[joaopapereira]

Closing since the work was already done