Don't panic when TempDir::new() fails

Author: kazk

src/imp/security_framework.rs

@@ -85,7 +85,7 @@ pub struct Identity {
 
 impl Identity {
     pub fn from_pkcs8(pem: &[u8], key: &[u8]) -> Result<Identity, Error> {
-        let dir = TempDir::new().unwrap();
+        let dir = TempDir::new().map_err(|_| Error(base::Error::from(errSecIO)))?;
         let keychain = keychain::CreateOptions::new()
                            .password("password")
                            .create(dir.path().join("identity.keychain"))?;