Added .NET Agent install

Created a new recipe for .NET Agent install. Downloads the latest .NET Agent from New Relic and installs in quiet mode. Utilizes the existing `node['newrelic']['application_monitoring']['license']` attribute for the license key and allows specifying install type via `node['newrelic']['dotnet']['install_level']` attribute (default is 1). The `node['newrelic']['dotnet']['https_download']` attribute defaults to always grab the latest build.