testing: added checker for actions in the database

Related to #397.
testing: improve isRecordedChecker

This improvement makes sure that the recorded action has a date, meaning
that it has been recorded using the rec.Log function.

Related to #397.
api: record user action in ServicesInstancesHandler

Related to #397.
api: rename ServicesInstancesHandler to serviceInstances

Related to #289.
api: record user action in CreateInstanceHandler

Related to #397.
api: rename CreateInstanceHandler to createServiceInstance

Related to #289.
api: record user action in bindSeviceInstance handler

Related to #397.
api: fix typo
api: record user action in unbindServiceInstance handler

Related to #397.
api: record user action in RemoveServiceInstanceHandler

Related to #397.
api: rename RemoveServiceInstanceHandler to removeServiceInstance

Related to #289.
api: record user action in ServiceInstanceStatusHandler

Related to #397.
api: remove useless check from ServiceInstanceStatusHandler
api: check for user authorization in ServiceInstanceStatusHandler

Fix #390.
api: rename ServiceInstanceStatusHandler to serviceInstanceStatus

Related to #289.