Update .travis.yml

`add` doesn't work with `pwd`. lets leave `clone` for now

Author: Evizero

.travis.yml

@@ -26,14 +26,14 @@ jobs:
       julia: 0.7
       os: linux
       script:
-        - julia -e 'import Pkg; Pkg.add(pwd()); Pkg.build("MLDatasets")'
+        - julia -e 'import Pkg; Pkg.clone(pwd()); Pkg.build("MLDatasets")'
         - julia -e 'import Pkg; Pkg.add("Documenter")'
         - julia -e 'import MLDatasets; ENV["DOCUMENTER_DEBUG"] = "true"; include(joinpath("docs","make.jl"))'
 
 ## uncomment the following lines to override the default test script
-script:
-    - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
-    - julia --check-bounds=yes --color=yes -e 'import Pkg; Pkg.add(pwd()); Pkg.build("MLDatasets"); Pkg.test("MLDatasets"; coverage=true)';
+#script:
+#    - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
+#    - julia --check-bounds=yes --color=yes -e 'import Pkg; Pkg.clone(pwd()); Pkg.build("MLDatasets"); Pkg.test("MLDatasets"; coverage=true)';
 
 after_success:
 - julia -e 'using Pkg; Pkg.add("Coverage"); using Coverage; Coveralls.submit(process_folder())'