Remove duplicate code from acceptance tests.

Just cleaning things up here.
diff --git a/acceptance/libargs.go b/acceptance/libargs.go
new file mode 100644
index 0000000..7b50f46
--- /dev/null
+++ b/acceptance/libargs.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+// getCredentials will verify existence of needed credential information
+// provided through environment variables.  This function will not return
+// if at least one piece of required information is missing.
+func getCredentials() (provider, username, password string) {
+	provider = os.Getenv("SDK_PROVIDER")
+	username = os.Getenv("SDK_USERNAME")
+	password = os.Getenv("SDK_PASSWORD")
+
+	if (provider == "") || (username == "") || (password == "") {
+		fmt.Fprintf(os.Stderr, "One or more of the following environment variables aren't set:\n")
+		fmt.Fprintf(os.Stderr, "  SDK_PROVIDER=\"%s\"\n", provider)
+		fmt.Fprintf(os.Stderr, "  SDK_USERNAME=\"%s\"\n", username)
+		fmt.Fprintf(os.Stderr, "  SDK_PASSWORD=\"%s\"\n", password)
+		os.Exit(1)
+	}
+
+	return
+}