Use MOI master

Author: blegat

.travis.yml

@@ -7,5 +7,7 @@ julia:
   - 1.1
 notifications:
   email: false
+before_script:
+  - julia -e 'using Pkg; Pkg.add(PackageSpec(name="MathOptInterface", rev="master"))'
 after_success:
   - julia -e 'import Pkg; Pkg.add("Coverage"); using Coverage; Coveralls.submit(process_folder()); Codecov.submit(process_folder())'