Updated tools version to 2.0.0

Also removed redundant lint-sanity (govet), and lint-style (gofmt), which are already checked by golangci-lint.
Also changed lint-mod slightly so it reverts any changes it makes go.mod, go.sum, and vendor/.

VOL-2647

Change-Id: Iaf53c43b0926d412f3f980dfb2d5944ff61ffb9c
diff --git a/docker/Dockerfile.openolt b/docker/Dockerfile.openolt
index 60d5b2c..3b0697b 100644
--- a/docker/Dockerfile.openolt
+++ b/docker/Dockerfile.openolt
@@ -15,10 +15,10 @@
 # -------------
 # Build stage
 
-FROM golang:1.12-alpine3.9 AS build-env
+FROM golang:1.13.8-alpine3.11 AS build-env
 
 # Install required packages
-RUN apk add --no-cache wget=1.20.3-r0 git=2.20.2-r0 make=4.2.1-r2 build-base=0.5-r1 protobuf=3.6.1-r1 protobuf-dev=3.6.1-r1
+RUN apk add --no-cache build-base=0.5-r1
 
 # Prepare directory structure
 WORKDIR /go/src
@@ -33,7 +33,6 @@
 
 # Build openolt
 SHELL ["/bin/ash", "-o", "pipefail", "-c"]
-ENV GO111MODULE=on
 RUN go build -mod=vendor -o /go/bin/openolt \
 	-ldflags \
 	"-X github.com/opencord/voltha-openolt-adapter/config/version.version=$org_label_schema_version \
@@ -47,7 +46,7 @@
 # -------------
 # Image creation stage
 
-FROM alpine:3.9.4
+FROM alpine:3.11.3
 
 # Set the working directory
 WORKDIR /app