Fix key store address hex decoding and accounts test

Thanks to https://github.com/jaekwon for original fix!

accounts/accounts_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestAccountManager(t *testing.T) {
-	ks := crypto.NewKeyStorePlain(ethutil.DefaultDataDir())
+	ks := crypto.NewKeyStorePlain(ethutil.DefaultDataDir() + "/testaccounts")
 	am := NewAccountManager(ks)
 	pass := "" // not used but required by API
 	a1, err := am.NewAccount(pass)
@@ -18,4 +18,16 @@ func TestAccountManager(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+
+	// Cleanup
+	accounts, err := am.Accounts()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, account := range accounts {
+		err := am.DeleteAccount(account.Address, pass)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
 }