dynamodb: Fix #212 Iterate over sorted keys by action for stable testing

[nabeken]

See http://golang.org/doc/go1.3#map

I got no error during several minutes with the following:

while true; do go test -v || break; done

@alimoeeny BTW, I hope travis to be back to this repository...

[alimoeeny]

thanks @nabeken for your time. Yeah, I am new to travis (I have some limited experience with drone). I will get back to you if I figured what is going on. We need to get the ci working before we can do anything meaningful with the pull requests. I am on it.

[nabeken]

@alimoeeny awesome, Travis seems working again:clap:

after_script in .travis.yml seems to be broken and then the build failed. I can rebase this branch once you're done with travis.

[alimoeeny]

@nabeken yes, please.