Revert "test a simplified travis.yml"

This reverts commit d0516ecb21.

nope, I do need the TARGET variable to know where the build goes anyway

.travis.yml

@@ -7,10 +7,15 @@ env:
   global:
     - PROJECT_NAME=http-server
 
-os:
+matrix:
-  - linux
+  include:
-  - osx
+    - os: osx
-  - windows
+      env: TARGET=x86_64-apple-darwin
+    - os: linux
+      env: TARGET=x86_64-unknown-linux-gnu
+    - os: windows
+      env: TARGET=x86_64-pc-windows-msvc
+
 
 script:
   - cargo build --target $TARGET