[#662] Fix submitter and duration values when importing data

* When we create a new instance based on a spreadsheet import request,
  we add the `submitter` and `surveyalTime`
[#662] Code improvement, use Long.valueOf directly

* Based on code review from @muloem
[#662] Add RELEASE NOTES for v1.7.0.3
Merge branch 'release/1.7.0'
Merge branch 'master' of https://github.com/akvo/akvo-flow into develop