search and download implemented; restructured features
improved code for downloads; added more tests for errors on downloads;
increased time for scenarios tagged "@downloads"
moved from `ydl feed` to `ydl add`; fixed some bugs;
removed references to pry
added configuration for travis-ci
moved `Ydl::Videos::Data` inside `Ydl::Videos`
refactored `Ydl::HouseKeeper`
refactored `Ydl::CLI`
refactored `Ydl::Delegator`
refactored `Ydl::Videos`
Refactored and created `Ydl::Searcher` class
refactored `Ydl::CLI` further
Refactored "Ydl::Videos" further
added badges for travis and codeclimate