#71 Check access token expiration

[josephdpurcell]

Fixes #71

[josephdpurcell]

I haven't tested this yet, I'll do that now.

[coveralls]

Coverage remained the same at 97.17% when pulling 498c9c7 on josephdpurcell:hotfix/1.1.1/check-access-token into e8b4c87 on typhonius:1.1.

[josephdpurcell]

I was able to test and confirm this works:

• When this patch is not applied and there is 300 seconds between requests the request fails.
• When this patch is applied and there is 300 seconds between requests the request succeeds.

[weitzman]

Thanks for backporting this massgov/openmass#390