[SD-1005] spike schema change
[SD-1005] Spike endpoints have been added
[SD-1010] Changed desk schema to add  spike expiry value
Merge branch 'master' of https://github.com/superdesk/superdesk-server
[SD-1010] Behave and unit tests added
[SD-1010] Behave and unit tests added
Merge pull request #335 from akintolga/master

API changes for spike
Removed unused spike service and refactored behave tests for spike
fix(build): fix flake8 issue