[travis] Update master spec repository before linting
[travis] Update master spec repository before linting

Since AlamofireImage has dependencies, we must update the spec
repository beforehand to make sure the correct versions of Alamofire
will be available during lint.

daniele-pizziconi/AlamofireImage,sessuru/AlamofireImage,easyui/AlamofireImage,daniele-pizziconi/AlamofireImage,easyui/AlamofireImage,Alamofire/AlamofireImage,Pluto-tv/AlamofireImage,Pluto-tv/AlamofireImage,Baza207/AlamofireImage,Alamofire/AlamofireImage,Baza207/AlamofireImage,sessuru/AlamofireImage