Go Modules cleanup; sarama upgrade

Clean-up indirect dependencies (#226)

sarama was causing some other indirect dependencies. Upgrading it fixes
the issue.

We now have 3 indirect dependencies listed in go.mod:

- github.com/go-logfmt/logfmt
- github.com/go-stack/stack
- gopkg.in/jcmturner/goidentity.v3

go-kit accounts for the first two and sarama for the last one. Since
sarama does support go modules, this may be something missing on their
side.

Fixing Go modules to deal with ocagent

go.mod: update ocagent to fix incorrect pseudo version (#225)

* go.mod: update ocagent to fix incorrect pseudo version

* update stackdriver

[server] avoiding memory usage issues when prometheus + stdlib router are used together

v1.2.12

[server] Avoiding Prometheus memory bomb when using the new stdlib ro…

[server] fixing health check panics while using stdlib router

[server] fixing stdlib router 😅 (#222)

* adding tests to fix stdlib router in server bc we shouldve done it from the start

* better test error msgs

[server] adding "stdlib" router

v1.2.10

adding a stdlib router to use in the server package (#221)

[auth] adding better errors [server/kit] adding leveled log messages

Adding log levels to kit/server.Log*Msg funcs (#220)

* adding log levels to kit/server.Log*Msg funcs. resolves #13

* adding warn and debug loggers, updating docs

* adding tests

Adding tools to make observing (and not observing) easier

v1.2.8

[observe] Adding RegisterAndObserveGCP to use within the SimpleServer…

[server/kit] adding the Google profiler in GCP enabled environments

v1.2.7

[server/kit] adding Google profiler if environment is GCP enabled (#214)

[auth] adding VerifyRequest

[auth] adding VerifyRequest for use within http middlewares (#213)

* [auth] adding VerifyRequest for use within http middleware

* drying up a tad

[server/kit] falling back to PORT if HTTP_PORT is not set

v1.2.5

falling back to PORT env variable if HTTP_PORT is not set (#212)