Changes to the imagename

[pieterlexis]

• Add -t option to specify image tag name
• Add -T option to specify image tag version, 'latest' by default. Can be set to 'version' to use $BUILDER_VERSION, used verbatim otherwise
• Clean up usage by categorizing options
• Sort the options in the getopts call and for statement

[wojas]

Tag images as builder-$repo-$target:$BUILDER_VERSION by default

I don't think this is a good idea. If you do this, builds will never be removed by the docker cleanup script, while simply using :latest by default will ensure that the previous build becomes untagged.

This should really be an opt-in thing.

[pieterlexis]

This should really be an opt-in thing.

Fixed in the latest commit

[Habbie]

This branch has conflicts that must be resolved.

[aerique]

Is this still needed?