[#258] updated warning alert text
[#194] fix for Dropbox backup crash

use a separate persistent store coordinator for backup to avoid potential problems in the managed object context connected to existing coordinator
fixed app ID for HockeyApp

apparently the ID changed when we switch to com.hivewallet.Hive identifier and the HockeyApp feature was broken since then... ಠ_ಠ
set company name for HockeyApp

used in the crash report copy, as "do you want to send a report to …"