ME: replaced 'formhub' references with 'ona'
ME: added documentation for downloading data as csv
Merge pull request #649 from onaio/631-document-data-download-as-csv

ME: added documentation for downloading data as csv
DW: Prepares onadata for the python json xls lib which will be added
DW: Added the python-json2xls lib and the test cases
DW: Replaces the / with _ on the field names
DW: Corrected the failing test
Dw: Added external_export in metadata and stores the external server url
DW: Query the data from postgres and not from mongodb
Dw: Code cleanup
DW: Can use either token or the token stored in the metadata
Initial ui changes
DW: add external export ui stuff
Dw: added a simple view to add and upload a template to the metadata
DW: resolved the failling tests
DW: Change the button labels for external export
UK: DW: return external export url or None, add export url only data_value is not None
UK/DW: code refactor
DW: Corrected failing tests and added template lists