The `to_h` method isn't calling keyify correctly

[cte]

https://github.com/taxjar/help_scout-sdk/blob/master/lib/help_scout/base.rb#L23

This should be:

result[HelpScout::Util.keyify(attribute[:name])] = attribute[:value]

Example:

[1] pry(main)> HelpScout::User.get(1).to_h
NoMethodError: undefined method `keyify' for #<HelpScout::User:0x00000000125dd6c8>