Add modules

This adds modules support so that we know what versions of our various
tools we are tracking.

Note that there are a lot of indirect dependencies added on part of the
fact we are pinning golang/protobuf at master (go get -u
github.com/golang/protobuf@master) to ensure that we don't run into
golang/protobuf#763.

go.mod

@@ -0,0 +1,58 @@
+module github.com/hashicorp/sentinel-sdk
+
+require (
+	cloud.google.com/go v0.35.1 // indirect
+	dmitri.shuralyov.com/app/changes v0.0.0-20181114035150-5af16e21babb // indirect
+	dmitri.shuralyov.com/service/change v0.0.0-20190127173012-184eb3bb42b2 // indirect
+	git.apache.org/thrift.git v0.12.0 // indirect
+	github.com/Shopify/sarama v1.20.1 // indirect
+	github.com/coreos/go-systemd v0.0.0-20181031085051-9002847aa142 // indirect
+	github.com/go-logfmt/logfmt v0.4.0 // indirect
+	github.com/gogo/protobuf v1.2.0 // indirect
+	github.com/golang/lint v0.0.0-20181217174547-8f45f776aaf1 // indirect
+	github.com/golang/protobuf v1.2.1-0.20190109072247-347cf4a86c1c
+	github.com/google/pprof v0.0.0-20190109223431-e84dfd68c163 // indirect
+	github.com/googleapis/gax-go v2.0.2+incompatible // indirect
+	github.com/gopherjs/gopherjs v0.0.0-20181103185306-d547d1d9531e // indirect
+	github.com/gorilla/mux v1.7.0 // indirect
+	github.com/gregjones/httpcache v0.0.0-20181110185634-c63ab54fda8f // indirect
+	github.com/grpc-ecosystem/grpc-gateway v1.7.0 // indirect
+	github.com/hashicorp/go-plugin v0.0.0-20190129155509-362c99b11937
+	github.com/microcosm-cc/bluemonday v1.0.2 // indirect
+	github.com/mitchellh/go-testing-interface v1.0.0
+	github.com/openzipkin/zipkin-go v0.1.5 // indirect
+	github.com/pkg/errors v0.8.1 // indirect
+	github.com/prometheus/client_model v0.0.0-20190115171406-56726106282f // indirect
+	github.com/prometheus/common v0.2.0 // indirect
+	github.com/prometheus/procfs v0.0.0-20190117184657-bf6a532e95b1 // indirect
+	github.com/russross/blackfriday v2.0.0+incompatible // indirect
+	github.com/shurcooL/go v0.0.0-20190121191506-3fef8c783dec // indirect
+	github.com/shurcooL/gofontwoff v0.0.0-20181114050219-180f79e6909d // indirect
+	github.com/shurcooL/highlight_diff v0.0.0-20181222201841-111da2e7d480 // indirect
+	github.com/shurcooL/highlight_go v0.0.0-20181215221002-9d8641ddf2e1 // indirect
+	github.com/shurcooL/home v0.0.0-20190127175526-fdd6870b8ab8 // indirect
+	github.com/shurcooL/htmlg v0.0.0-20190120222857-1e8a37b806f3 // indirect
+	github.com/shurcooL/httpfs v0.0.0-20181222201310-74dc9339e414 // indirect
+	github.com/shurcooL/issues v0.0.0-20190120000219-08d8dadf8acb // indirect
+	github.com/shurcooL/issuesapp v0.0.0-20181229001453-b8198a402c58 // indirect
+	github.com/shurcooL/notifications v0.0.0-20181111060504-bcc2b3082a7a // indirect
+	github.com/shurcooL/octicon v0.0.0-20181222203144-9ff1a4cf27f4 // indirect
+	github.com/shurcooL/reactions v0.0.0-20181222204718-145cd5e7f3d1 // indirect
+	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
+	github.com/shurcooL/webdavfs v0.0.0-20181215192745-5988b2d638f6 // indirect
+	github.com/sirupsen/logrus v1.3.0 // indirect
+	github.com/stretchr/testify v1.3.0
+	go.opencensus.io v0.19.0 // indirect
+	go4.org v0.0.0-20181109185143-00e24f1b2599 // indirect
+	golang.org/x/build v0.0.0-20190128191652-269e03abe74b // indirect
+	golang.org/x/crypto v0.0.0-20190129170551-bf88e3f4ba72 // indirect
+	golang.org/x/exp v0.0.0-20190125153040-c74c464bbbf2 // indirect
+	golang.org/x/net v0.0.0-20190125091013-d26f9f9a57f3
+	golang.org/x/oauth2 v0.0.0-20190115181402-5dab4167f31c // indirect
+	golang.org/x/perf v0.0.0-20190124201629-844a5f5b46f4 // indirect
+	golang.org/x/tools v0.0.0-20190128232029-0a99049195af // indirect
+	google.golang.org/genproto v0.0.0-20190128161407-8ac453e89fca // indirect
+	google.golang.org/grpc v1.18.0
+	honnef.co/go/tools v0.0.0-20190128043916-71123fcbb8fe // indirect
+	sourcegraph.com/sqs/pbtypes v1.0.0 // indirect
+)