Update retrofit to 1.9.0.
Update retrofit to 1.9.0.

- https://github.com/square/retrofit/blob/master/CHANGELOG.md#version-190-2015-01-07

UweTrottmann/SeriesGuide,0359xiaodong/SeriesGuide,hoanganhx86/SeriesGuide,epiphany27/SeriesGuide,artemnikitin/SeriesGuide,UweTrottmann/SeriesGuide,r00t-user/SeriesGuide