Move tests out of travis config to a standalone script

Can also be used as a pre-commit hook.

.travis.yml

@@ -26,8 +26,4 @@ before_script:
 
 sudo: false
 script:
-  - go install -v ./cmd/cashier ./cmd/cashierd
-  - go list ./... |grep -v vendor/ |xargs go test
-  - gofmt -d $(find -type f -name '*.go' -not -path './vendor/*')
-  - go list ./... |grep -v vendor/ |xargs go vet
-  - go list ./... |grep -v vendor/ |xargs -L1 golint -set_exit_status
+  - ./run_tests.sh

run_tests.sh

+#! /bin/sh
+
+# This can be used as a pre-commit script.  Just run
+#   cp run_tests.sh .git/hooks/pre-commit
+# and it will run before each commit.
+
+set -xue
+
+go install -v ./cmd/cashier ./cmd/cashierd
+go list ./... |grep -v vendor/ |xargs go test
+gofmt -d $(find * -type f -name '*.go' -not -path 'vendor/*')
+go list ./... |grep -v vendor/ |xargs go vet
+if ! type -f golint > /dev/null; then
+  go get -u github.com/golang/lint/golint
+fi
+go list ./... |grep -v vendor/ |xargs -L1 golint -set_exit_status