ruby-openid useless requirement

[PedroLopes]

rake db:migrate shouts an error about installing ruby-openid gem.

Commenting the gem line in the "config/envirionment.rb" doesn't solve it

[dzacarias]

Although it's not used, there are several places in the code that would need to be cleaned up before removing this dependance.

I suggest we keep it for now, commenting out the UI parts that use OpenID. That is to say: install this gem in the meantime.