Group Travis jobs (in .travis.yml) by operating system instead of by Julia version.

Author: kernelmethod

.travis.yml

@@ -13,28 +13,25 @@ jobs:
     - os: windows
   include:
     ###### Tests
-    ### Julia 1.0
+    ### Linux
     - stage: "Unit tests"
       julia: 1.0
       os: linux
       script:
         -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
 
-    ### Julia 1.1
     - stage: "Unit tests"
       julia: 1.1
       os: linux
       script:
         -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
 
-    ### Julia 1.2
     - stage: "Unit tests"
       julia: 1.2
       os: linux
       script:
         -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
 
-    ### Julia 1.3
     - stage: "Unit tests"
       julia: 1.3
       os: linux
@@ -47,21 +44,15 @@ jobs:
         - julia -e 'using Coverage; Codecov.submit(Codecov.process_folder());'
 
     - stage: # Unit tests
-      julia: 1.3
-      os: osx
+      julia: nightly
+      os: linux
       script:
         -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
 
+    ### OSX
     - stage: # Unit tests
       julia: 1.3
-      os: windows
-      script:
-        -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
-
-    ### Julia nightly
-    - stage: # Unit tests
-      julia: nightly
-      os: linux
+      os: osx
       script:
         -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
 
@@ -72,6 +63,13 @@ jobs:
         - julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
       julia: nightly
 
+    ### Windows
+    - stage: # Unit tests
+      julia: 1.3
+      os: windows
+      script:
+        -  julia --color=yes -e 'using Pkg; Pkg.activate(); Pkg.instantiate(); Pkg.test()'
+
     - stage: # Unit tests
       os: windows
       script: