Rails 4.1 compatibility - change way we include Sorcery::Model
Change way of running travis tests

In order to properly run tests for Rails 4.1 we need to have separate gemfiles
for MongoMapper and Mongoid (conflict of gem versions). In order to handle this
  properly I decided to change the way we run tests. This change will allow to
  later add separate Gemfiles for Rails 4.1
exclude datamapper tests with rails4 ruby 2.1
Merge branch 'improve_travis_matrix' into rails_4_1_fix
add rails 4.1 builds and gemfiles to travis
Run spec suite under MRI 2.1.2

/cc @arnvald
support scopes for VK oauth provider
do not duplicate attr_accessor line
Fix session timeout to work with Rails cookie store

Rails cookie-based default session store represents times as Strings, which must be converted to times before comparison.
update AR Rails 4.1 gemfile to actually have Rails 4.1
Use new ActiveSupport::Callbacks::Chain

In Rails 4.1 the chain class wraps an object @chain, which stores the
information about the callbacks. We use this class for deleting before and after
filters that should be called only for specific submodules. Therefore we need to
check for the Rails version and decide which way to use.

Anyway, this way of removing callbacks is not very pretty. Let's look for
something better soon.
User User.first instead of User.find(:first)

The `find` method does not accept :first option to find first user, it treats
parameter as user's id. Therefore we need to use `first` method
Merge remote-tracking branch 'nateberkopec/master' into rails_4_1_fix
fix double condition line in session timeout
update additional builds to ruby 2.1.2
Merge pull request #544 from arnvald/improve_travis_matrix

Change way of running travis tests
Merge branch 'master' into rails_4_1_fix
Merge pull request #538 from arnvald/rails_4_1_fix

Rails 4.1 compatibility
add Rails 4.1 fixes info to CHANGELOG
remove locks and add them to gitignore