[#54] Add CSV validation function
[#54] Fix validation CSV validation function
[#54] Remove empty strings from the counts
[#54] WIP import data from CSV into SQLite DB
[#54] WIP - Create nodes in GAE based on SQLite DB data
[#54] WIP - Performance improvements on SQLite -> GAE

* Usa a memory cache when building the entities collection (up to
  page-size elements)
* Precompute the data for used for creating nodes, each level has
  a nodes_n table
* Make a bulk insert on mappings, instead of one by one
[#54] Small code improvement to prevent duplicated paths
[#54] Improvements on handling upload requests
[#54] Make use of create-nodes after validating csv file

* parentNodeId and cascadeResourceId are Longs
[#54] Adds support for importing CSV without code column
[#54] Make sure we have the proper type for using Long/valueOf
[#54] Send message to GAE when cascade import fails
[#54] Notify GAE on cascade publishing success/failure
[#54] fix typo
Merge pull request #55 from akvo/feature/54-import-cascade-csv

Feature/54 import cascade csv