adds php 7.2 to travis

[bshaffer]

No description provided.

[bluebaroncanada]

I'm worried this commit or commits like it could cause other logical statements to trigger. For example: null checks.

[bluebaroncanada]

It might not just be internal code that's affected by this change, too.

[bluebaroncanada]

Never mind. It shouldn't be an issue. My apologies.

[bluebaroncanada]

Err. Actually it is if $a=[]; $a===null;

[bshaffer]

You bring up a good point. $server->getResponseType and $server->getGrantType will be returning differently with this change. It may be time we rename master to v1-master, and rename develop to master and merge in the changes from the v2 branch.

[bshaffer]

@bluebaroncanada This change is very benign. We should look into moving to v2.0 soon, however!