Expose bug in AccessToken
Expose bug in AccessToken

Some properties in AccessToken have either wrong decorators or don't
catch necessary exceptions.

Add testcases that expose bugs in these properties.

Change-Id: I5897f31786317dae6534c89fa41a38f6cb15a168
Partial-Bug: 1477327

jamielennox/keystoneauth,sileht/keystoneauth