Adds appveyor for windows build

appveyor.yml

@@ -0,0 +1,11 @@
+version: 0.{build}
+skip_tags: true
+cache: C:\Users\appveyor\AppData\Local\NuGet\Cache
+build_script:
+- SET GOPATH=c:\workspace
+- go test -v -race ./...
+test: off
+clone_folder: c:\workspace\src\github.com\hpcloud\tail
+branches:
+  only:
+  - master