Added appveyor instructions for building project

SimpleBase.sln

@@ -3,14 +3,15 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 15
 VisualStudioVersion = 15.0.26711.1
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SimpleBase", "src\SimpleBase.csproj", "{A9C1CF86-32B3-40E6-A51A-3E6D17C15EE3}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SimpleBase", "src\SimpleBase.csproj", "{A9C1CF86-32B3-40E6-A51A-3E6D17C15EE3}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SimpleBaseTest", "test\SimpleBaseTest.csproj", "{617BA86D-31E2-41EA-A1C8-E37602D58C07}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{4ECCE094-D6EC-4938-A209-FA9B78AED7DA}"
 	ProjectSection(SolutionItems) = preProject
 		.gitignore = .gitignore
 		.travis.yml = .travis.yml
+		appveyor.yml = appveyor.yml
 		LICENSE.txt = LICENSE.txt
 		README.md = README.md
 		SimpleBase.nuspec = SimpleBase.nuspec

appveyor.yml

@@ -0,0 +1,9 @@
+image: Visual Studio 2017
+before_build:
+- cmd: >-
+    appveyor DownloadFile https://dist.nuget.org/win-x86-commandline/latest/nuget.exe
+
+    nuget restore
+build:
+  parallel: true
+  verbosity: normal