bower.json: remove moot `version` field
bower.json: remove moot `version` field

Per https://github.com/bower/bower.json-spec/commit/a325da3d79baab018c572d75dc1781b12322f6cd
roidelapluie/primer,loki315zx/primer,Cartman0/primer,primer/primer-css,fac/origin,Alanaktion/primer,MSch/primer,primer/primer,marcelosomers/primer,df2k2/primer,primer/primer-css,ilovezy/primer,dushmis/primer,tarebyte/primer,andrewmowe/primer,waern/primer,fac/origin,timv88/primer,primer/primer,primer/primer,primer/primer-css,primer-cn/primer-cn,tehp/primer,ryanjm/primer