Rename StatisticsQuery to BackupQuery

The helper class wll be used in a subsequent request in
ProjectBackupResource to specify time periods for partial
backups, so StatisticsQuery would no longer be appropriate.

Change-Id: I2f24e0932df7cf4ffd53f606fe6078ef2696eb53
Signed-off-by: Michael Ochmann <michael.ochmann@sap.com>
6 files changed