Add migrate to docker (#26)

With these changes, those who might want to execute migrations on other containers will be able to since all necessary files are available in the docker image

Co-authored-by: João Bologna <joao.bologna@wildlifestudios.com>

Dockerfile

@@ -11,16 +11,20 @@ RUN go mod download
 
 COPY . .
 RUN make build
+RUN CGO_ENABLED=0 GOOS=linux go build -pkgdir=$GOPATH/pkg/mod/ -tags 'postgres' -o bin/migrate \
+	github.com/golang-migrate/migrate/v4/cmd/migrate
 
 FROM alpine:3.10
 
 RUN apk add --no-cache ca-certificates
-  
+
 WORKDIR /app
 
 COPY --from=build-env /Will.IAM/bin/Will.IAM /app
 COPY --from=build-env /Will.IAM/config /app/config
 COPY --from=build-env /Will.IAM/assets /app/assets
+COPY --from=build-env /Will.IAM/migrations /app/postgres/migrations
+COPY --from=build-env /Will.IAM/bin/migrate /app/postgres
 
 EXPOSE 4040