ci: modernize travis config

.travis.yml

 os:
-    - linux
-    - osx
+  - linux
+
+sudo: false
 
 language: go
 
 go:
-    - 1.8
+    - 1.9.x
 
-install: true
+install:
+  - make deps
 
 script:
-    - make deps
-    - gx-go rewrite
-    - go get github.com/mattn/goveralls
-    - goveralls -service=travis-ci
+  - bash <(curl -s https://raw.githubusercontent.com/ipfs/ci-helpers/master/travis-ci/run-standard-tests.sh)
 
 cache:
     directories:
         - $GOPATH/src/gx
+
+notifications:
+  email: false
+
+env: GOTFLAGS="-race -cpu=5"

Makefile

-test: deps
-	go test -race -v ./...
-
 export IPFS_API ?= v04x.ipfs.io
 
 gx:
@@ -10,5 +7,3 @@ gx:
 deps: gx
 	gx --verbose install --global
 	gx-go rewrite
-	go get -t ./...
-