Merge pull request #591 from modilabs/update-propagation-590

Update propagation 590
fix req file location in fab script
when deleting of updating an observation set deleted_at but do not remove, closes #587
for all existing indices also add multi-index with deleted_at
isolate deleted_at code in Observation model
move version check command to bottom, rarely needed
migration to add deleted_at to all existing observations
Merge pull request #588 from modilabs/pure-edits-587

On observation (row) update and delete do not remove data