[#239] Class for handling memcache in safe way

* provides initiation of memcache
* provides putObject within try-catch
[#239] Add question order and question group order properties

* 'questionOrder' and 'questionGroupOrder' added to SurveyalValue
* 'order' added to placemarkDetailDto
* 'order' added to placemarkDetail models in client
[#239] Method to bulk populate order fields in legacy data

* This methods runs over all surveyalValues in the datastore
and populates the questionOrder and questionGroupOrder properties
[#239] Populate order fields when surveyalValue object is created

* also includes refactor of the way surveyalValues are constructed,
now a lookup table is used to find the questions.
[#239] Move bulk computation to DataProcessorRestServlet
[#239] Generic method to list all objects of kind using pagesize
[#239] Allow bulk recompilation on specific survey

* This is requested in issue #539
[#239] add surveyId property to surveyalValues

* we need this so we can recompute orders by surveyId
[#239] Check for null value of orders
[#249] Testharness action to fire order recompute task
[#249] Recompute orders
[#239] Code cleanup, adds documentation

* Use a single static member for logging
* Adds documentation for the developer on the implications of using
  `putObject`
[#239] Log a warning when using non initialized cache

* This could help us identify code paths that are broken
[#239] Code clean up

* Use final variables
* Don't overwrite the value of the parameter `cursor`
* Formatting
[#239] Code clean up

* Refactor logic to exit early when nothing to do
* Use `final` variables when possible
* Fix logic to schedule a task only if the current size of the list is
  equal to the MAX length, and not everytime the size is larger than
  zero
[#239] Code cleanup

* Removes duplicated code in `listAll`, and use only `list`
* Adapt new code to use `list` method
* Some backward compatible methods are now available, since we now list
  requires a `pageSize` as parameter
[#239] Process data in `dataprocessor` backend
[#239] Implement `containsKey` with exception handling

* Implement `containsKey` helper function with built-in exception
  handling
[#239] `containsKey` already handles null value for cache
Merge pull request #538 from akvo/feature/239

Feature/239 - Show questions in proper order on map.