Add continuous integration

[gregmac]

Adds a CI build proces using AppVeyor, including badges for the project build status and nuget package. This PR also does some cleanup.

Change Summary

• Moves the Test project to the top-level (instead of nested inside the main project)
• Uses the Github VisualStudio gitignore file
• Adds AppVeyor.yml configuration to build nuget package and run tests

• Adds AppVeyor badge to README (Example from my fork)

  

• Adds Nuget badge to README:

  

  Additional Steps

Note after merging this there are two additional steps to take:

1. Create a new AppVeyor project that is linked to the actual https://github.com/jsakamoto/ipaddressrange repository (instead of my fork)
2. Update the badge link in the README to point at the badge for this new project (under AppVeyor > Project > Settings > Badges > Markdown link)

Once this is done it's also possible to automate publishing to nuget.org (including conditional so only a 'release' branch publishes and with secure api keys).

[jsakamoto]

Thank you for your pull request.

I'm trying to create a new AppVeyor account, and studying about it, and etc. etc..

Please give me more few days.

Thanks!

[gregmac]

Let me know if you want any assistance. We could just use my account, but it's your project so you should probably retain control of the builds, and setting up at AppVeyor is pretty simple anyway.

[jsakamoto]

I merged :smile: https://twitter.com/jsakamoto/status/613689521096384512

I'll try to automate publishing to nuget.org at a later date (may be after changing construtors).