ci: run matrix build with go 1.7.x - 1.x

The .travis.yml file has been updated so that CI will also attempt to
build the kernel using the latest go branches from 1.7, 1.8, 1.9, 1.10,
1.x.

The tests will only be run once against the latest go version.

.travis.yml

@@ -1,9 +1,29 @@
 language: go
 sudo: required
+addons:
+  apt:
+    packages:
+    - nasm
+    - binutils-2.26
+# Compile kernel with various go versions
 go:
+  - 1.7.x
+  - 1.8.x
+  - 1.9.x
+  - 1.10.x
   - 1.x
-script:
+stage: build kernel
+before_install:
+  - export PATH=/usr/lib/binutils-2.26/bin:${PATH}
+script: make kernel
+
+# Run the tests against the latest go version
+jobs:
+  include:
+    - stage: run tests
+      go: 1.x
+      script:
         - make lint
         - make collect-coverage
-after_success:
+      after_success:
         - bash <(curl -s https://codecov.io/bash)