OmniAuth Action Controller Error
class AuthenticationsController < ApplicationController

    def index
      @authentications = current_user.authentications if current_user
    end

    def create
      auth = request.env["omniauth.auth"]
      current_user.authentications.find_or_create_by_provider_and_uid(auth['provider'],auth['uid'])
     flash[:notice] = "Authentication successful."
      redirect_to authentications_url
    end

   def destroy
      @authentication = current_user.authentications.find(params[:id])
      @authentication.destroy
      flash[:notice] = "Successfully destroyed authentication."
      redirect_to authentications_url
   end

ProjectManage::Application.routes.draw do |map|
  match '/auth/:provider/callback' => 'authentications#create'
  devise_for :users
  resources :projects
  resources :tasks
  resources :authentications  # <-- This is the one you're missing
  root :to => 'projects#index'
end