authenticate: remove extra login page (#34)

- Fixed a bug where Lifetime TTL was set to a minute.
- Remove nested mux in authenticate handlers.
- Remove extra ping endpoint in authenticate and proxy.
- Simplified sign in flow with multi-catch case statement.
- Removed debugging logging.
- Broke out cmd/pomerium options into own file.
- Renamed msicreant cipher to just cipher.

Closes #23

proxy/handlers_test.go

@@ -0,0 +1,27 @@
+package proxy
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestProxy_RobotsTxt(t *testing.T) {
+	auth := Proxy{}
+	req, err := http.NewRequest("GET", "/robots.txt", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rr := httptest.NewRecorder()
+	handler := http.HandlerFunc(auth.RobotsTxt)
+	handler.ServeHTTP(rr, req)
+	if status := rr.Code; status != http.StatusOK {
+		t.Errorf("handler returned wrong status code: got %v want %v", status, http.StatusOK)
+	}
+	expected := fmt.Sprintf("User-agent: *\nDisallow: /")
+	if rr.Body.String() != expected {
+		t.Errorf("handler returned wrong body: got %v want %v", rr.Body.String(), expected)
+
+	}
+}