Update codesign to use updated cert

Makefile

@@ -6,7 +6,7 @@ GOVERSION=$(shell go version)
 GOBIN=$(shell go env GOBIN)
 VERSION=$(shell git describe --tags --candidates=1 --dirty)
 FLAGS=-X main.Version=$(VERSION) -s -w
-CERT="3rd Party Mac Developer Application: 99designs Inc (NRM9HVJ62Z)"
+CERT="Developer ID Application: 99designs Inc (NRM9HVJ62Z)"
 SRC=$(shell find . -name '*.go')
 
 build:
@@ -26,3 +26,6 @@ $(BIN)-windows-386: $(SRC)
 
 release: $(BIN)-linux-amd64 $(BIN)-darwin-amd64 $(BIN)-windows-386
 	codesign -s $(CERT) $(BIN)-darwin-amd64
+
+clean:
+	rm -rf $(BIN)-linux-amd64 $(BIN)-darwin-amd64 $(BIN)-windows-386

README.md

@@ -11,12 +11,14 @@ Download the [latest release](https://github.com/99designs/aws-vault/releases).
 
 On macOS, you may instead use [homebrew cask](https://github.com/caskroom/homebrew-cask) to install:
 
-    brew cask install aws-vault
+    $ brew cask install aws-vault
 
 The macOS release is code-signed, and you can verify this with `codesign`:
 
-    codesign -dvvv $(which aws-vault) | grep NRM9HVJ62Z
-    Authority=3rd Party Mac Developer Application: 99designs Inc (NRM9HVJ62Z)
+    $ codesign -dvv $(which aws-vault) 2>&1 | grep Authority
+    Authority=Developer ID Application: 99designs Inc (NRM9HVJ62Z)
+    Authority=Developer ID Certification Authority
+    Authority=Apple Root CA
 
 ## Usage