Call AWS.config.update after parsing region

[sonya]

The README suggests that the options.region parameter is not required when specifying an arn for the lambda_deploy task. However, I was finding this not to be the case, and it looked like what was happening was the region was being set before it was parsed from the arn. This PR attempts to fix this.

[Tim-B]

My apologies for the delay in replying to this. Would it be possible to add unit tests to demonstrate this fixes the issue? Otherwise I might break it again in future ;)

[sonya]

Thanks for looking at this. I added a unit test which indeed fails if the previous commit is reverted.

[rnowosielski]

@Tim-B how about merging this? I spent quite some time today trying to figure out why the tooling thinks my lambda doesn't exist even though it did exists :)

[mahirk]

@Tim-B Any possible update for the above?