Updated build script to include code coverage

Author: sharwell

.nuget/packages.config

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="NuGet.CommandLine" version="2.8.3" />
+  <package id="OpenCover" version="4.6.247-rc" />
+</packages>

README.md

@@ -4,4 +4,6 @@
 
 [![Build status](https://ci.appveyor.com/api/projects/status/0f0w76hunsj3es8p/branch/master?svg=true)](https://ci.appveyor.com/project/sharwell/asyncusageanalyzers/branch/master)
 
+[![codecov.io](https://codecov.io/github/DotNetAnalyzers/AsyncUsageAnalyzers/coverage.svg?branch=master)](https://codecov.io/github/DotNetAnalyzers/AsyncUsageAnalyzers?branch=master)
+
 This repository contains analyzers for best practices related to asynchronous programming. Where possible, code fixes are also provided to simplify the process of correcting violations.

appveyor.yml

@@ -1,10 +1,19 @@
 version: 1.0.{build}
-os: Visual Studio 2015 CTP 6
+os: Visual Studio 2015
 init:
 - git config --global core.autocrlf true
 install:
 - set PATH=C:\Program Files (x86)\MSBuild\14.0\Bin;%PATH%
 before_build:
 - nuget restore
 build:
+  project: AsyncUsageAnalyzers.sln
   verbosity: minimal
+test_script:
+- .\packages\OpenCover.4.6.247-rc\tools\OpenCover.Console.exe -register:user -target:"%xunit20%\xunit.console.x86.exe" -targetargs:"C:\projects\asyncusageanalyzers\AsyncUsageAnalyzers\AsyncUsageAnalyzers.Test\bin\Debug\AsyncUsageAnalyzers.Test.dll -noshadow -appveyor" -returntargetcode -filter:"+[AsyncUsage*]*" -excludebyattribute:*.ExcludeFromCodeCoverage* -hideskipped:All -output:.\AsyncUsageAnalyzers_coverage.xml
+- "SET PATH=C:\\Python34;C:\\Python34\\Scripts;%PATH%"
+- pip install codecov
+- codecov -f "AsyncUsageAnalyzers_coverage.xml"
+# preserve "packages" directory in the root of build folder but will reset it if packages.config is modified
+cache:
+  - packages -> **\packages.config