Add argument to add tags to STS session

[lpearson-trek10]

Something similar to what you would do if you were adding tags when calling aws sts assume-role

--tags Key=mykey,Value=myvalue Key=mykey2,Value=myvalue2

[ryansb]

It would be nice to support a kwarg-style key=value to make it easy to do interactively for simple alphanumeric pairs. The verbose Key=mykey,Value= should only be for cases where you've got odd spacing or quoting.

[pbinczyk-lcloud]

I've also noted the need to tag STS sessions. Just prepared a ready PR with this solution: https://github.com/trek10inc/awsume/pull/216

It would be great to see it merged ;)

[mtskillman]

closed by https://github.com/trek10inc/awsume/pull/225