Fix regex for custom messages module

[exeto]

When you have an application that is listed lower in the registry than ember-validations/messages, custom messages module will fail

Reproduction steps:

1. Generate new ember app that starts with a lower alpha character - i.e ember new zebra-app
2. Install ember-validations
3. Install all dependencies needed for ember-changeset-validations
4. Provide a custom messages module i.e. - zebra-app/app/validations/messages
5. Try to use validations, and you will see that custom messages does not get used

Description taken from #144

[exeto]

@poteto Hi. This project is not supported?

[nucleartide]

@exeto Could you explain what this accomplishes? Sorry – I haven't looked through what this code does.

[exeto]

@nucleartide I updated the message.

[nucleartide]

@exeto Ahh, I see what you mean. The regex will match ember-validations/messages before it matches zebra-app/validations/messages.

I think a more robust solution would be to match on the app name directly. Would you mind modifying the regex to include modulePrefix or APP.name from config/environment? This StackOverflow answer has some approaches to getting the ENV.

[exeto]

@nucleartide Done

[nucleartide]

@exeto Excellent work, thanks!

[exeto]

@nucleartide thanks