upgrading linter from gometalinter to golangci-lint (#2100)

* upgrading linter from gometalinter to golangci-lint

* fixed golangci-lint linting

* removed linting before_script command

* removed disable-all command

* Fixed golang config file

* fixed golang config file v2

* removed gosec issue rule

* formatting

* fixed travis build to run golangci-lint

* Add install golangci-lint command

* fixing golangci-lint script

* removed https://

* Added golangci-lint cmd script

* added go get for local lint install

* created a before_script

* add install before script

* Added get script

* added go mod download

* removed go mod downloads

* changed

* removed before script

* Added before script go get lint

* added exit zero to see what went wrong

* removed golang run script

* removed before script

* change lint command

* verbose output

* removed verbose

* change linter enable and disable configuration

* Update .golangci.yml

Removed gotype as a linter

* Update .golangci.yml

Added typecheck linter

* Update .golangci.yml

Added fixed lint version

* Update .golangci.yml

Added gotype

* Update .golangci.yml

Added typecheck

* removed env:lint

* Added env lint

* fixing lint upgrade

* Changing travis configuration

* FIxed spelling errors

* disabled typecheck

* Enabled typecheck

* remove binary

* Deleting lib binary

* adding more linters

* fixed constants

* fix spelling

* fixed all lint issues

* Revert "Changing travis configuration"

This reverts commit 334afe9d05.

* Merge branch 'master' of https://github.com/prysmaticlabs/prysm into update-linter

* Changed from Infof to Info

* Fixing commits

* fixing commits with linter config

* added install

* Fixing

* fix log statement

.golangci.yml

@@ -0,0 +1,69 @@
+linters-settings:
+  govet:
+    check-shadowing: true
+    settings:
+      printf:
+        funcs:
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Infof
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Warnf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Errorf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Fatalf
+  golint:
+    min-confidence: 0
+  gocyclo:
+    min-complexity: 10
+  maligned:
+    suggest-new: true
+  dupl:
+    threshold: 100
+  goconst:
+    min-len: 2
+    min-occurrences: 2
+  depguard:
+    list-type: blacklist
+    packages:
+      # logging is allowed only by logutils.Log, logrus
+      # is allowed to use only in logutils package
+      - github.com/sirupsen/logrus
+  misspell:
+    locale: US
+  lll:
+    line-length: 140
+  goimports:
+    local-prefixes: github.com/golangci/golangci-lint
+  gocritic:
+    enabled-tags:
+      - performance
+      - style
+      - experimental
+    disabled-checks:
+      - wrapperFunc
+
+linters:
+  enable:
+    - deadcode
+    - goconst
+    - goimports
+    - golint
+    - gosec
+    - misspell
+    - structcheck
+    - typecheck
+    - unparam
+    - varcheck
+    - gofmt
+    - unused
+  disable-all: true
+
+run:
+  skip-dirs:
+    - proto/
+    - ^contracts/
+  deadline: 10m
+
+# golangci.com configuration
+# https://github.com/golangci/golangci/wiki/Configuration
+service:
+  golangci-lint-version: 1.15.0 # use the fixed version to not introduce new linters unexpectedly
+  prepare:
+    - echo "here I can run custom commands, but no preparation needed for this repo"