Additional error information in the event of a COM error.

Example:

    var win32ole = require('win32ole');
    var db = win32ole.client.Dispatch('ADODB.Connection');
    db.Provider = "Microsoft.Jet.OLEDB.4.0";
    db.Open("nofile.mdb");

Output:

OLE error: [Open] -2147352567 [Open] = [10]
**Microsoft JET Database Engine: Could not find file 'D:\git\nodejsplay\nofile.mdb'.**
(It always seems to be appeared at that time you mistake calling'obj.get { ocv->getProp() }' <-> 'obj.call{ocv->invoke() }'.) IDispatch::Invoke AutoWrap() failed

TypeError: node_win32ole::V8Variant::OLEInvoke failed
    at Object.<anonymous> (D:\git\nodejsplay\test.js:4:4)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
        at node.js:901:3

This suggested patch may also help to address issue #5