Reduce number of envionments to test in appveyor

Building and testing all the different windows environments against
stable/beta/nightly would take too long.  Reducing the environments msvc &
gnu 64 bit environments for beta and 1.9.0 rust

README.md

@@ -2,6 +2,7 @@
 [![Build Status](https://travis-ci.org/kkawakam/rustyline.svg?branch=master)](https://travis-ci.org/kkawakam/rustyline)
 [![Clippy Linting Result](https://clippy.bashy.io/github/kkawakam/rustyline/master/badge.svg)](https://clippy.bashy.io/github/kkawakam/rustyline/master/log)
 [![](http://meritbadge.herokuapp.com/rustyline)](https://crates.io/crates/rustyline)
+[![Build status](https://ci.appveyor.com/api/projects/status/ls7sty8nt25rdfkq/branch/master?svg=true)](https://ci.appveyor.com/project/kkawakam/rustyline/branch/master)
 
 Readline implementation in Rust that is based on [Antirez' Linenoise](https://github.com/antirez/linenoise)
 

appveyor.yml

 environment:
   matrix:
   - TARGET: 1.9.0-x86_64-pc-windows-msvc
-  - TARGET: 1.9.0-i686-pc-windows-msvc
   - TARGET: 1.9.0-x86_64-pc-windows-gnu
-  - TARGET: 1.9.0-i686-pc-windows-gnu
   - TARGET: beta-x86_64-pc-windows-msvc
-  - TARGET: beta-i686-pc-windows-msvc
   - TARGET: beta-x86_64-pc-windows-gnu
-  - TARGET: beta-i686-pc-windows-gnu
-  - TARGET: nightly-x86_64-pc-windows-msvc
-  - TARGET: nightly-i686-pc-windows-msvc
-  - TARGET: nightly-x86_64-pc-windows-gnu
-  - TARGET: nightly-i686-pc-windows-gnu
 install:
   - ps: Start-FileDownload "https://static.rust-lang.org/dist/rust-${env:TARGET}.exe"
   - rust-%TARGET%.exe /VERYSILENT /NORESTART /DIR="C:\Program Files (x86)\Rust"