Update to v1.5.7.0

Quick update to block Dropbox updates to v2.1.6 and v2.1.7.
If you are receiving the Dropbox update to stable version v2.0.2 or v2.0.4, please contact me through the contact page, because I did not receive any of these updates.

Furthermore, I recommend to opt-out of receiving beta updates by going to the and unchecking the “Include me on early releases” checkbox under “Account preferences”.