[SDK][Android] Release v4.7.0

Add contact synchronization: the SDK now syncs the contact with the WonderPush servers and uses it for segmentation and in-app messages. It is active by default and can be turned off with the syncDisabled setting
Expose the synced contact payload publicly
Fix date comparisons in segmentation: field values are now coerced to dates when compared against a date criterion
Fix a crash when OkHttp raised an exception that was not an IOException