Update to latest apispec

[bugeats]

Several versions behind now, and it's causing conflicts.

[izieg-lo3]

I have found apispec-chalice to be very useful, but the deeper I get into it I'm finding it difficult to use because it's hard to find the right documentation for older versions of apispec.

[mathewmarcus]

@bugeats @izieg-lo3 you are absolutely right, apispec-chalice does need to be updated to be compatible with the newer versions of apispec. Unfortunately, I do not have the capacity to do this at the moment. Would either of you be interested in submitting a PR? If not, I'll get to it as soon as I can.

[jordan-dimov]

Any update on this?