Adds .ruby-version and .ruby-gemset files to ignored git files

* rvm changed rvm ruby version declaration
Major revision changes on Models

* Changes PurchaseItem in favor of LineItem
* Creates a Transaction model where Payment and Purchase inherit from.
* Begin specing models.
* Changes database schema to reflect model changes as well as adds
  sensitive defaults.
Overrides to Backbone.sync method

* Overrides Backbone.sync to make use of authentication token provided
  through gon js object.
* Changes Customer model and Customers collection to make use of the
  API route.
Adds a user authentication token to the gon js object.
Using the API CustomersController

* Removes temporary CustomersController in app namespace.
* Edits Customer entities to use Routes.api_customers_path().
Edits List.CustomerRow template for better handling of Customer#balance.
Adds ActiveModelSerializers to define JSON output on models.

* Adds Active Model Serializers
* Configures Active Model Serializers to not use root element.
Edits API controllers JSON output

* Edits API routes.
* Adds base serializers for Customer, Payment, Purchase, LineItem.
* Relates User to Payment, Purchase through Customer.
* Edits API controller responses to scope by User related records
  depending on provided authentication token.
Specifies ruby version on Gemfile.
Adds documentation

* First serious effort in documenting the API.
* Brief explanation of several setup steps.
Sets 127.0.0.1 as server to accept requests in documentation
Adds basic registration endpoint to the API.
Model callbacks

* Adds several computed callbacks to Payment, Purchase.
* Removes old purchases and payments tables from database to avoid
  collisions arising from similar model names.
* Edits LineItem and Payment factories.
* Creates seed data.
Completes Customer full view in frontend app.

* Adds base Transaction views to be rendered on each model.transactions
  instance from calling /api/customers/:id
* Adds empty Badi.Entities.Transaction and
  Badi.Entities.TransactionsCollection
* Fixes routing problems.
* Adds routes for signing up from the API.
* Edits links on frontend to avoid collisions from uninitialized
  controllers on rails.
* Adds accounting.js and moment.js to help format timestamps
  and currency.
Small fix to README.
Documents API on Customer#create, Customer#update.
Adds handlebars_assets gem

* Implementing handlebars_assets gem to help us transition to Handlebars
  templates for our Marionette views.
* Loads handlebars.runtime in application.js manifest.
Implements Handlebars in all existing Marionette views.

* Configures Marionette.Renderer to use HandlebarsTemplates instead
  of JST.
* Registers two helpers to format currency and dates on Handlebars.
* Converts existing template files to Handlebars templates.
Merge pull request #11 from antillas21/develop

Develop