lib/high_voltage.rb should be able to be required.

Currently the main library file ```lib/high_voltage.rb``` can't be required since it uses the ```mattr_accessor``` method from the ```active_support``` gem.

Requiring ```high_voltage``` results in the following error:

	[1] pry(main)> require 'high_voltage'
	NoMethodError: undefined method `mattr_accessor' for HighVoltage:Module
	from /home/linduxed/Documents/thoughtbot/high_voltage/lib/high_voltage.rb:8:in `<module:HighVoltage>'

```require 'active_support/core_ext'``` solves the problem, but might be loading too much.