Increate .travis.yml consistency between repos

- aspnet/Universe#349
- minimize `dotnet` setup time; no need for caching
- build with `--quiet`

.travis.yml

@@ -10,6 +10,10 @@ addons:
     - libssl-dev
     - libunwind8
     - zlib1g
+env:
+  global:
+    - DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
+    - DOTNET_CLI_TELEMETRY_OPTOUT: 1
 mono:
   - 4.0.5
 os:
@@ -25,7 +29,7 @@ branches:
 before_install:
   - if test "$TRAVIS_OS_NAME" == "osx"; then brew update; brew install openssl; ln -s /usr/local/opt/openssl/lib/libcrypto.1.0.0.dylib /usr/local/lib/; ln -s /usr/local/opt/openssl/lib/libssl.1.0.0.dylib /usr/local/lib/; fi
 script:
-  - ./build.sh verify
+  - ./build.sh --quiet verify
 notifications:
   webhooks:
     secure: "UiVaDFq+8X2my/h8kIMjYvd93bFJiEJIjJCx6C+h9xeJDrM2Y4+e+kLnoxFVmI89+nAiRk4gSGEWrtVhJtWwp26o7+FGKqoCIIsUwvRB/alrEhLxPlI0Pf2YE34hwHmQlKpntBCB+4pmfTgDiLtz30i6NieeEM4aRubx7x6MOLQ="