add coverage and osx

Author: SimonDanisch

.travis.yml

@@ -1,7 +1,15 @@
 language: julia
 sudo: false
+os:
+  - linux
+  - osx
 julia:
   - nightly
   - 0.4
 notifications:
   - email: false
+script:
+    - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
+    - julia --inline=no -e 'Pkg.clone(pwd()); Pkg.test("Contour"; coverage=true)'
+after_success:
+  - julia -e 'cd(Pkg.dir("Contour")); Pkg.add("Coverage"); using Coverage; Coveralls.submit(process_folder()); Codecov.submit(process_folder())'