gemspec + delivery_method (+ Added Bearer to Authorization header)

[AndyObtiva]

I setup project for submitting to rubygem and generated a gemspec for it. This was done using Jeweler and Bundler. Also incorporated authorization bearer to fix issue with token used in API requests (as per #5). Thank you very much for providing this library. You should be able to submit as a rubygem by pulling this pull request into your local directory, merging, and running "rake release". Let me know if you need any help with this as I have released many gems in the past. I look forward to future versions of this library.

p.s. I tested the gem hosted on my github fork using this line in a project Gemfile:

gem 'sendpulse-rest-api-ruby', git: 'https://github.com/AndyObtiva/sendpulse-rest-api-ruby.git'

It worked! In the future, developers should be able to just reference the gem once released as follows:

gem 'sendpulse-rest-api-ruby'

or

gem 'sendpulse-rest-api-ruby', '~> 1.0.0'

Finally, a Rails ActionMailer delivery_method (:sendpulse) has been added to leverage the sendpulse-rest-api-ruby for email sending in Rails with minimal setup. Details are found in the updated README.md

[brunomperes]

[miguelpeniche]

Hey @AndyObtiva, is this still working?