Gemfile.lock should not be check in

Please see
http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
for more details
Introduce a simple API DSL

This is desirable when you don't want to mix Vero directly into your
models, and do not desire the verbosity of accessing the API modules
directly. Example usage:

  class UsersController < ApplicationController
    include Vero::DSL

    def update
      vero.users.track!({ ... })
    end
  end
Improve validation messages

Validations were just throwing a stringified hash which did not help
the use of the gem.

Replaced validations with explicit checks and corresponding messages.
Added some missing specs.
Merge pull request #26 from jherdman/remove-gemfile-lock

Gemfile.lock should not be check in
Merge pull request #27 from swalberg/improve_validation_messages

Improve validation messages
Adjusted gem spec.
Merge pull request #25 from jherdman/introduce-api-dsl

Introduce a Simple API DSL
Updated read me with new DSL instructions.
Bump
fixes #28
Bump