version bump to 1.11.0
version bump to 1.11.0

add artist#get_images (see https://github.com/youpy/ruby-lastfm/pull/41)

youpy/ruby-lastfm,alexis779/ruby-lastfm,ShanaLMoore/ruby-lastfm,volontarian/ruby-lastfm,Bopster/ruby-lastfm,jjgh/ruby-lastfm