Increase .travis.yml consistency between repos

- aspnet/Universe#349
- minimize `dotnet` setup time; no need for caching
- install packages used in other repos; explicit and avoids issues as (Beta) Trusty image changes

.travis.yml

@@ -4,7 +4,16 @@ dist: trusty
 addons:
   apt:
     packages:
+    - gettext
+    - libcurl4-openssl-dev
+    - libicu-dev
+    - libssl-dev
     - libunwind8
+    - zlib1g
+env:
+  global:
+    - DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
+    - DOTNET_CLI_TELEMETRY_OPTOUT: 1
 mono:
   - 4.0.5
 os: