Getting 'undefined method `to_sym' while migrating while setting up Devise - ruby-on-rails

Question

I am trying to set up Pageflow. Finally I managed to create DBs and install pageflow. I can run rails s but I get Migrations are pending; run 'bin/rake db:migrate RAILS_ENV=development' to resolve this issue. in my browser.
Anyway, typing bundle exec rake db:create db:migrate would give me this error:
== AddDeviseToUsers: migrating ===============================================
-- change_table(:users)
rake aborted!
StandardError: An error has occurred, all later migrations canceled:
undefined method `to_sym' for {:null=>false, :default=>""}:Hash/Users/user/.gem/gems/activerecord-4.0.2/lib/active_record/connection_adapters/abstract/schema_statements.rb:671:in `type_to_sql'
This line in schema_statements says.
def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
if native = native_database_types[type.to_sym]
column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup
if type == :decimal # ignore limit, use precision and scale
scale ||= native[:scale]
if precision ||= native[:precision]
if scale
column_type_sql << "(#{precision},#{scale})"
else
column_type_sql << "(#{precision})"
end
elsif scale
raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale is specified"
end
elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
column_type_sql << "(#{limit})"
end
column_type_sql
else
type
end
end
I tried to solve this with the gem composite-primary-keys, but found out that there is no compatible version for rails 4.0.2.
Being an absolute noob, I found the issue here: https://github.com/composite-primary-keys/composite_primary_keys/issues/174 but it didn't helped me out.
Thanks!
//EDIT
Thats my user.rb:
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :token_authenticatable, :confirmable,
# :lockable, :timeoutable and :omniauthable
devise :database_authenticatable,
:recoverable, :rememberable, :trackable, :validatable
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable,
:recoverable, :rememberable, :trackable, :validatable
include Pageflow::UserMixin
end
There is no extra comma at the end...