Port pgoutput to modules (#3)

Since pgoutput is a library, we shouldn't be committing our vendor directory. Instead, add a go.mod file a tag a 0.1.0 release.

Author: kyleconroy

Gopkg.lock

@@ -0,0 +1,7 @@
+module github.com/kyleconroy/pgoutput
+
+require (
+	github.com/google/go-cmp v0.2.0
+	github.com/jackc/pgx v3.2.0+incompatible
+	github.com/pkg/errors v0.8.0 // indirect
+)

Gopkg.toml

@@ -0,0 +1,6 @@
+github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
+github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/jackc/pgx v3.2.0+incompatible h1:0Vihzu20St42/UDsvZGdNE6jak7oi/UOeMzwMPHkgFY=
+github.com/jackc/pgx v3.2.0+incompatible/go.mod h1:0ZGrqGqkRlliWnWB4zKnWtjbSWbGkVEFm4TeybAXq+I=
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=