Update to support Omnipay version 3

[erictompkins]

Can you please update the library to support Omnipay version 3

https://github.com/thephpleague/omnipay

Please see https://github.com/thephpleague/omnipay-common/blob/master/UPGRADE.md

Thank you!

[lchoate]

I second this issue. If someone was willing to point me to some resources, I'd do a PR but I've never done one publicly and don't want to do it wrong.

I think the issue is PHP7 support, what else? How do I contribute to the project?

[dmgctrlr]

It would be great to see this supporting v3

[mfauveau]

Hi guys, I'm no longer employed by the company that was using this gateway. Therefore I have no need/time to work on it.
Feel free to do a PR or fork the repo.

[mfauveau]

@lchoate https://help.github.com/articles/about-pull-requests/

[SHELA]

@mfauveau Hello check please PR. for 3x version
Thank you