KETTLE-20: Improvements to error handling both within and outside requests in Kettle. Improved commenting for test helpers as well as some of core framework. NOTE: This fix is blocked by a fix to FLUID-5254
KETTLE-20: Tidied up stray logging messages, updated to version of infusion with working "afterDestroy" event
GPII-609: Improvements to Kettle to allow native session handling to be optional in test utilities, fixes for socket.io session implementation, improvement in error handling
Merge remote-tracking branch 'amb26/GPII-609'

* amb26/GPII-609:
  GPII-609: Improvements to Kettle to allow native session handling to be optional in test utilities, fixes for socket.io session implementation, improvement in error handling
  KETTLE-20: Tidied up stray logging messages, updated to version of infusion with working "afterDestroy" event
  KETTLE-20: Improvements to error handling both within and outside requests in Kettle. Improved commenting for test helpers as well as some of core framework. NOTE: This fix is blocked by a fix to FLUID-5254