Fix Travis (#51)

See https://discourse.julialang.org/t/travis-ci-configuration-breaking-changes/34268/3. Also test Julia 1.4 instead of 1.2.

.travis.yml

@@ -6,16 +6,10 @@ os:
 
 julia:
   - 1.0
-  - 1.1
-  - 1.2
+  - 1.3
+  - 1.4
   - nightly
 
-# # Uncomment the following lines to allow failures on nightly julia
-# # (tests will run but not make your overall status red)
-# matrix:
-#   allow_failures:
-#   - julia: nightly
-
 notifications:
   email: false
 
@@ -28,6 +22,10 @@ after_success:
 #  - julia -e 'using Pkg; Pkg.add("Coverage"); using Coverage; Codecov.submit(Codecov.process_folder())';
 
 jobs:
+# # Uncomment the following lines to allow failures on nightly julia
+# # (tests will run but not make your overall status red)
+# allow_failures:
+#   - julia: nightly
   include:
     - stage: "Documentation"
       julia: 1.0