Golang DB admin

[rawlinp]

What does this PR do?

Add a golang implementation of the TO db/admin.pl script. Vendor the gopkg.in/yaml.v2 package for parsing the dbconf.yml file (the config file for goose). Build the golang executable into the TO rpm next to the db/admin.pl script. Add a deprecation warning to the db/admin.pl script to use the db/admin binary instead. Add a docker environment for running DB tests (uses the golang db/admin binary to test the sql migrations, seeds, patches, etc).

Which TC components are affected by this PR?

• Documentation
• Grove
• Traffic Analytics
• Traffic Monitor
• Traffic Ops
• Traffic Ops ORT
• Traffic Portal
• Traffic Router
• Traffic Stats
• Traffic Vault
• Other _________

What is the best way to verify this PR?

Pull down this PR locally and:

cd traffic_ops/app/db
go build admin.go
cd ..
db/admin <insert arg here>

Go back and forth between using db/admin and db/admin.pl to verify that the behavior of the same arguments is the same for both.
Run the provided DB test using docker-compose (pass it a traffic_ops.rpm and initial DB dump from your local TO instance):

To build and copy the traffic_ops.rpm:
./pkg -v traffic_ops_build
cp dist/traffic_ops-* traffic_ops_db/test/docker/traffic_ops.rpm

To grab an initial DB dump and place it for the test, use the <insert your TO hostname here>/api/1.3/dbdump endpoint and copy the response to traffic_ops_db/test/docker/initdb.d/.
Then run the tests w/ docker-compose:

cd traffic_ops_db/test/docker
docker-compose build
docker-compose up --exit-code-from trafficops-db-admin

Check all that apply

• This PR includes tests
• This PR includes documentation updates
• This PR includes an update to CHANGELOG.md
• This PR includes all required license headers
• This PR includes a database migration (ensure that migration sequence is correct)
• This PR fixes a serious security flaw. Read more: www.apache.org/security

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/trafficcontrol-PR/2825/
Test FAILed.

[ezelkow1]

Tested with a dummy migration and could see the up/down being tested

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/trafficcontrol-PR/2934/
Test PASSed.

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/trafficcontrol-PR/2935/
Test PASSed.

[dangogh]

tested in cdn-in-a-box -- all commands worked as advertised..