Manager should accept identifiers in urls with and without 0x prefix

[elboletaire]

Bug description

Backend will start generating all urls without 0x, but we still need to give backwards compatibility, allowing urls with and without the 0x

Steps to reproduce

• Create a process in the manager (stage), setting the web poll to on, with a valid census and at least one valid user to receive the e-mail
• As soon as you receive the e-mail for the webpoll, you'll see it's format is like https://manager.stg.vocdoni.net/processes/vote/#/0x{id}/{id}/0x{id}
• It won't load due to the identifier in the middle not having the prefixed 0x

Current behavior

It fails loading processes where one or many 0x where missing.

Expected behavior

Should load with and without 0x in any of the three identifiers provided in the url.

System:

• Browser: irrelevant
• Commit hash: latest

[elboletaire]

This is actually in issue with dvote-js and dvote-solidity not accepting (yet) non hex prefixed strings. I'll create issues there to properly track it.