Add tags argument parser for aws_cli

[gursewak1997]

Add the ability to add tags to AMIs when running ore aws upload with --tags flag. Can be used as: cosa buildextend-aws --tags foo=bar,abc=xyz or cosa buildextend-aws --tags=foo=bar --tags=abc=xyz

[dustymabe]

Can be used as: cosa buildextend-aws --tags foo=bar,abc=xyz or cosa buildextend-aws --tags="foo=bar,abc=xyz"

I would say:

Can be used as: cosa buildextend-aws --tags foo=bar,abc=xyz or cosa buildextend-aws --tags=foo=bar --tags=abc=xyz

[gursewak1997]

I would say:

Can be used as: cosa buildextend-aws --tags foo=bar,abc=xyz or cosa buildextend-aws --tags=foo=bar --tags=abc=xyz

Unfortunately that doesn't work but let me see if I can make changes to implement that. Adding multiple --tags ends up only taking the last value.

[gursewak1997]

I can make changes to implement that.

The new changes should take care of the above.

[dustymabe]

The changes LGTM, but let's "fix" the grant-user* args in an initial (separate) commit to explain things a little better.