Remove ruby version from Gemfile

[arthurnn]

It is not a good idea to have a ruby version on the Gemfile, specially if you are using RVM,
as rvm sets ENV[RUBY_VERSION] using the revision number: ex.: ruby-2.0.0-p247 , which does not work

review @shingara

[coveralls]

Coverage increased (+0.77%) when pulling 929a2d1 on ruby_version into 39c486a on master.

[shingara]

I understand you concern about rvm. I not using rvm so I didn't know this issue. Sorry. I do this adding to force the usage of 2.0.0 in heroku. Maybe we can use another ENV variable instead of RUBY_VERSION and only if you use the HEROKU or USE_ENV variable set to true. like :

ruby (ENV['ERRBIT_RUBY_VERSION'] || '2.0.0') if ENV['HEROKU'] || ENV['USE_ENV']

in heroku the default ruby is 1.9.2 and it's not compatible to mongoid 3. So we can't deploy on heroku without change the Gemfile. But I want keep this simple deploiement on heroku behavior.

What do you think about this change ?

[arthurnn]

I think the default on heroku is 2.0.0 by now: https://blog.heroku.com/archives/2013/6/17/ruby-2-default-new-aps

[shingara]

Ok, I merge it. But we need delete some other information in documentation about that.

[arthurnn]

Ok, double checking the docs right now.