Release DUB 1.1.1

[Sönke Ludwig via Digitalmars-d-announce]

Together with DMD 2.072.1, DUB 1.1.1 has been released. Binaries are 
included in the DMD distribution and are also available separately on 
https://code.dlang.org/download.

This patch release includes some fixes for issues with optional and path 
based dependency resolution.

Full change log:
https://github.com/D-Programming-Language/dub/blob/master/CHANGELOG.md