Bootstrap2 dependency patch. Include bootstrap statically to make it possible using bootstrap3 in your local application

I include bootstrap statically in rails_admin

The following files are not necessary i think because they are not includes in app/assets/stylesheets/rails_admin/rails_admin.scss.erb:
 - bootstrap.css
 - bootstrap.min.css
 - bootstrap-response.css
 - bootstrap-responsive.min.css

In other respects every application wich mount rails_admin will load this static bootstrap files.
Additionally i rename the bootstrap directory to bootstrap2 and adjust all bootstrap includes in assets/stylesheets/rails_admin/rails_admin.scss.erb  

I think rails_admin only need the bootstrap directory because rails_admin.scss.erb doesn't include other files. 
I think my branch is now stable with that patch and rails applications can be used with bootstrap3.