fix bad custom error generation

[Yvem]

The new custom error HttpError doesn't behave as an error, mainly by missing properties stack and name.

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error#Custom_Error_Types
• http://stackoverflow.com/questions/1382107/whats-a-good-way-to-extend-error-in-javascript

[chpill]

🆗

[goldo]

🆗

[Yvem]

@neoziro a release would be much welcome

[Yvem]

thanks !