Add same regex as client to address validation

[chq-matteo]

While we think of a better solution, add a regex to validate the urls
appirio-tech/connect-app#1426
We can use joi to do that
https://github.com/hapijs/joi#example
For the regex see
https://github.com/appirio-tech/react-components/blob/feature/connectv2/components/Formsy/index.js#L14

[chq-matteo]

To verify

1. monitor the browser the requests
2. add a valid link
3. edit the request to some invalid address
4. send the request
5. see if the request is rejected

[chq-matteo]

Since probably we will use more regexes multiple times, I moved it in the constant.js file under the REGEX "namespace"