The page "Verify Contract" ask for "Constructor Arguments ABI-encoded".
In your case the constructor has no parameters, so you can leave such field empty.
In the general case when your constrctor has parameters you can proceed as follow:
You can use ethereumjs-abi to encode/decode the parameters for transaction calls.
Let's suppose your constructor is MyToken(address _to, uint256 _value, bool _enabled). The parameters types are ["address", "uint256", "bool"].
If you have created the contract MyToken("0x1234567812345678", 0x314159268, true). Then the parameters values are ["0x1234567812345678", "0x314159268", true].
Then you can encode the values with rawEncode(parameterTypes, parameterValues).
var abi = require('ethereumjs-abi')
var parameterTypes = ["address", "uint256", "bool"];
var parameterValues = ["0x1234567812345678", "0x314159268", true];
var encoded = abi.rawEncode(parameterTypes, parameterValues);
console.log(encoded.toString('hex'));
On execution it will output
000000000000000000000000000000000000000000000000123456781234567800000000000000000000000000000000000000000000000000000003141592680000000000000000000000000000000000000000000000000000000000000001
Best Answer
In case you want to use a simple online tool to encode parameters you could use https://abi.hashex.org
You insert the abi code to automatically parse parameters types or just enter them manually. In Function type selector constructor should be picked.
Here is an example, at the bottom are abi-encoded parameters that you enter in etherscan.io constructor parameters field input.