Support `alignment` in config file

[hcopperm]

Version info

• intercom-rails version: latest
• Rails version: 4.2.10

Expected behavior

Passing in config.alignment in the config file should change the alignment of the widget.

Actual behavior

The Rails app won't start, because 'alignment' is not a supported config option.

Steps to reproduce

1. Add config.alignment = 'left' to your intercom-rails config file
2. Start app

Logs

/Users/amitree/workspace/amitree/config/initializers/intercom_rails.rb:8:in `block in <top (required)>': undefined
method `alignment=' for IntercomRails::Config:Class (NoMethodError)

Notes

You can get around this error by putting alignment in config.user.custom_data

  config.user.custom_data = {
    'alignment' => Proc.new { |_current_user| 'left' },
  ...
  }

This is undocumented and not obvious, and also it is unclear if it will have unknown side effects.