travis environment and dotnet version

.travis.yml

@@ -5,12 +5,13 @@ env:
   global:
   - DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
   - DOTNET_CLI_TELEMETRY_OPTOUT: 1
+  matrix:
+    secure: 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
 mono: none
-dotnet: 2.1
+dotnet: 2.1.300
 os:
 - linux
 - osx
-- windows
 osx_image: xcode8.2
 addons:
   apt: