Cleanup the Api Module

- No other module in the whole of wikibase uses
  camelCase for parameters so I have made the
  entityType param now be entitytype so as not
  to confuse people

- The module name also before use camelCase, this
  was inconsistent with the example provided in the
  module itself and again is inconsisten with every
  other api module so I have lowered the case.

- Also the entity ID in the exmaple now uses Upper
  case

Change-Id: Ib631a598c7c784a6e12adec4e169504e4b13bba6
Merge "Cleanup the Api Module"