Add paket checks to CI

.travis.yml

@@ -13,6 +13,8 @@ before_script:
 
 script:
   - travis_wait ./build.sh NuGet
+  - mono .paket/paket.exe install
+  - git diff --exit-code
 
 after_script:
   - mono --debug --profile=log:coverage,covfilter=+OpenTK,covfilter=-OpenTK.Tests,covfilter=-FSharp.Core,covfilter=-FsCheck,covfilter=-xunit.assert "packages/xunit.runner.console/tools/xunit.console.exe"  "tests/OpenTK.Tests/bin/Release/OpenTK.Tests.dll" -parallel none

appveyor.yml

@@ -3,6 +3,8 @@ init:
   - git config --global core.autocrlf input
 build_script:
   - cmd: build.cmd NuGet
+  - cmd: .paket\paket.exe install
+  - cmd: git diff --exit-code
 test: off
 version: 0.0.1.{build}
 artifacts: