message: Reduce builds on windows and osx to full check
  We don't gain any interesting insight with feature flag combinations
  other than 'all features' (the default). Still builds on stable and
  nightly, but not beta, and 1.24.1 so that we are (somewhat) warned when
  a dependency requires updating the minimum compiler version.
diff: @@ -4,8 +4,6 @@ notifications:
  irc: "irc.mozilla.org#piston-internals"
  os:
  - linux
  - - osx
  - - windows
  rust:
  - 1.24.1
  - stable
  @@ -24,6 +22,20 @@ env:
  - FEATURES='tiff'
  - FEATURES='webp'
  - FEATURES='hdr'
  +matrix:
  + include:
  + - os: osx
  + rust: 1.24.1
  + - os: windows
  + rust: 1.24.1
  + - os: osx
  + rust: stable
  + - os: windows
  + rust: stable
  + - os: osx
  + rust: nightly
  + - os: windows
  + rust: nightly
  script:
  - if [ -z "$FEATURES" ]; then
  cargo build -v &&
  