Increased version to 2.0.0-beta-10

Signed-off-by: Michalis Vitos <info@michalisvitos.gr>
Minor fix in FileHelpers

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>
Renamed "data" folder to "attachments"

Some improvements to back-up feature:
- Moved back-up code out of ProjectManagerActivity and into separate helper class BackupDialogBuilder
- using only localisable strings from strings.xml instead of hardcoded
- made Zipper work with File objects instead of path Strings

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>
Merge branch 'master' of github.com:ExCiteS/Sapelli