Checks that a model is not abstract before all 
Checks that a model is not abstract before all 

Fixes #46.
voormedia/rails-erd,mallikarjunayaddala/rails-erd,qiujuer/rails-erd,nalabjp/rails-erd,sferik/rails-erd,kerrizor/rails-erd,qiujuer/rails-erd,mallikarjunayaddala/rails-erd,voormedia/rails-erd,sferik/rails-erd,nalabjp/rails-erd,kerrizor/rails-erd