Add root Exception to the bug signature.
Enhancing view dedicated to bug aggregates
Add a view to retrieve app version codes list. Required for purge by app version code.
Update README.md
New view to list reports by bug.
Merge branch 'master' of https://github.com/ACRA/acra-storage
Add description field to bugs
Various fixes for ACRA/acralyzer#37, ensuring that a valid crash date is saved in database, and that a corrupted crash date won't block acralyzer.
Add installation_id to digest reports.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	validate_doc_update.js
	views/reports-per-day/map.js