travis: use multiple build stages

This change rewrites .travis.yml to use many build stages/jobs. This
allows our build to run faster, as almost all jobs run in containers.

Stage 1: Run on all pushes to all branches
  - Job Build: just runs "make" to make sure everything is OK

Stage 2: Run on all PRs and pushes to master
  - Job Lint: Makes sure dep, "make gen", "make format", and "make lint"
              are all happy.
  - Job Build 1: Make sure "go get" and "make" will work. This job will
                 later run unit tests.
  - Job Build 2: Same as Job Build 1, except with another go version.
  - Job Integeration: Run integration tests (needs sudo, so needs VM)

Stage 3: Run on releases (if other stages pass)
  - Job Deploy: Publishes amd64 binaries to GitHub.

1 files changed, 25 insertions, 0 deletions

diff --git a/bin/files-changed b/bin/files-changed
new file mode 100755
index 0000000..3ffbad6
--- /dev/null
+++ b/bin/files-changed
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+# Detect if any files have changed in the git repository. Output an appropriate
+# error message if they have changed.
+
+if [[ -n $(git status -s) ]]; then
+  git diff --minimal HEAD
+  echo
+  echo "**************************************************"
+  case "$1" in
+  "proto")
+    echo "* .pb.go files and .proto files are out of sync. *"
+    echo "*        Run \"make gen\" to generate them.        *"
+    ;;
+  "format")
+    echo "*    C or Go files have incorrect formatting.    *"
+    echo "*         Run \"make format\" to fix them.         *"
+    ;;
+  *)
+    echo "*     Files have changed in this repository.     *"
+    ;;
+  esac
+  echo "**************************************************"
+  git reset HEAD --hard
+  exit 1
+fi
\ No newline at end of file