[WIP] Cleaning up underused and non-recommended code (nytimes#171)

Cleaning up underused and non-recommended code

adding an iss field to IAM tokens (nytimes#172)

[server/kit] adding NewLogger to use for background logging + updated…

… docs (nytimes#170)

* adding NewLogger to use for background logging + upped kit docs

* doc cleanup

* removing tab from docs

* p->P

[auth/gcp] allowing IAMConfig to override default Google credentials (n…

…ytimes#169)

* IAM going to provide my own JSON sometimes

* using the proper token source

[server/kit] adding protobuf go-kit funcs to mimic NYTimes/marvin (ny…

…times#167)

* [server/kit] adding protobuf go-kit funcs to mimic NYTimes/marvin

* lint!

Update sqs constructor to allow custom endpoint (nytimes#166)

To allow for mocking of SQS queues a configurable endpoint is required.
For SNS this has already been done, this is just adding the same for
SQS.

 [server/kit] adding automatic error reporting for any panics encount…

…ered (nytimes#164)

* [server/kit] adding automatic error reporting

* better error message

* no longer overwriting panic error, missing log keys

* updating mods, adding error handler for error reporting

changing requestRoleCredentials (nytimes#162)

* changing requestRoleCredentials

* remove duration since it's default anyways'

* removing idea

Prioritize Role over environment variables (nytimes#161)

* Update aws.go

* add also to subscriber

actually passing the email this time