remove NflxCredentialsProviderChain

This is an old class that basically setup credentials
using environment variables supporting a token so it
could work with IAM credentials. More recent versions
of the AWS SDK have ProfileCredentialsProvider in the
DefaultAWSCredentialsProviderChain.

Also adds some helper scripts to create the config file
from the output of the metadata services.
Merge pull request #33 from brharrington/aws-credentials

remove NflxCredentialsProviderChain
minor updates to build and release

Hopefully this will get the build working right:

* Fixes: Invalid POM: /com/netflix/atlas/atlas-json/1.4.1/atlas-json-1.4.1.pom: Developer information missing
* Fixes: Missing Signature: '/com/netflix/atlas/atlas-json/1.4.1/atlas-json-1.4.1.pom.asc' does not exist for 'atlas-json-1.4.1.pom'.
* Update sbt-pgp version
Merge pull request #35 from brharrington/sbt-pgp-version

minor updates to build and release
avoid repetition of uri
update dependency versions
Merge pull request #36 from brharrington/tag-suite-reuse

avoid repetition of uri
change build link to be the history tab
Merge pull request #37 from brharrington/deps-update

update dependency versions
Merge pull request #38 from brharrington/build-link

change build link to be the history tab