Final tweaks to ci/travis config

- Remove appveyor badge from readme
- Allow release key to be used from Travis

.travis.yml

@@ -20,7 +20,7 @@ matrix:
       # Workaround for a Travis caching bug on Windows where absolute paths
       # are not restored from caches properly:
       # https://github.com/travis-ci/casher/pull/38
-      env: STACK_ROOT=$TRAVIS_BUILD_DIR/.stack_root RELEASE_KEY=
+      env: STACK_ROOT=$TRAVIS_BUILD_DIR/.stack_root
       # workaround for https://travis-ci.community/t/windows-instances-hanging-before-install/250/15
       # We also zero out the RELEASE_KEY environment variable above to reduce
       # the risk of accidentally leaking it.

README.md

@@ -2,7 +2,7 @@
 
 A small strongly typed programming language with expressive types that compiles to JavaScript, written in and inspired by Haskell.
 
-[![Hackage](https://img.shields.io/hackage/v/purescript.svg)](http://hackage.haskell.org/package/purescript) [![Build Status](https://api.travis-ci.org/purescript/purescript.svg?branch=master)](http://travis-ci.org/purescript/purescript) [![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/purescript/purescript?branch=master&svg=true)](https://ci.appveyor.com/project/hdgarrood/purescript-lfgff/history)
+[![Hackage](https://img.shields.io/hackage/v/purescript.svg)](http://hackage.haskell.org/package/purescript) [![Build Status](https://api.travis-ci.org/purescript/purescript.svg?branch=master)](http://travis-ci.org/purescript/purescript)
 
 ## Language info