Update README.md

Replaced "Mono Latest" with "Mono & .NET Core"
Added appveyor test badge
Replaced nuget badge

Author: Aragas

README.md

@@ -1,6 +1,6 @@
-**Mono Latest:** | **.NET 4.5 & .NET Core:** | **NuGet** | **Codecov** | **COVERALLS**
+**Mono & .NET Core:** | **.NET 4.5 & .NET Core:** | **NuGet** | **Codecov** | **COVERALLS**
 ------------ | ------------- | ------------- | ------------- | -------------
- | [![Build Status](https://travis-ci.org/PCLExt/PCLExt.FileStorage.svg?branch=master)](https://travis-ci.org/PCLExt/PCLExt.FileStorage) | [![Build status](https://ci.appveyor.com/api/projects/status/puku2ym0k1n7ryde?svg=true)](https://ci.appveyor.com/project/Aragas/pclext-filestorage) | [![nugetpkg](https://img.shields.io/badge/nuget-PCLExt.FileStorage-orange.svg)](https://www.nuget.org/packages/PCLExt.FileStorage) | [![Coverage Status](https://coveralls.io/repos/github/PCLExt/PCLExt.FileStorage/badge.svg?branch=master)](https://coveralls.io/github/PCLExt/PCLExt.FileStorage?branch=master) | [![codecov](https://codecov.io/gh/PCLExt/PCLExt.FileStorage/branch/master/graph/badge.svg)](https://codecov.io/gh/PCLExt/PCLExt.FileStorage)
+ | [![Build Status](https://travis-ci.org/PCLExt/PCLExt.FileStorage.svg?branch=master)](https://travis-ci.org/PCLExt/PCLExt.FileStorage) | [![Build status](https://ci.appveyor.com/api/projects/status/puku2ym0k1n7ryde?svg=true)](https://ci.appveyor.com/project/Aragas/pclext-filestorage) [![AppVeyor tests](https://img.shields.io/appveyor/tests/Aragas/pclext-filestorage.svg)]() | [![NuGet](https://img.shields.io/nuget/v/PCLExt.FileStorage.svg)]() | [![Coverage Status](https://coveralls.io/repos/github/PCLExt/PCLExt.FileStorage/badge.svg?branch=master)](https://coveralls.io/github/PCLExt/PCLExt.FileStorage?branch=master) | [![codecov](https://codecov.io/gh/PCLExt/PCLExt.FileStorage/branch/master/graph/badge.svg)](https://codecov.io/gh/PCLExt/PCLExt.FileStorage)
 
 # PCLExt.FileStorage