Run the Revise tests on travis

The package is so tightly integrated with Revise, we'd better know
immediately if we've broken something in Revise.

Author: timholy

.travis.yml

@@ -20,6 +20,9 @@ notifications:
 script:
     - export JULIA_PROJECT=""
     - julia --project -e 'using Pkg; Pkg.build(); Pkg.test();'
+    - julia -e 'using Pkg; Pkg.develop(PackageSpec(path="."));
+                           Pkg.add(PackageSpec(url="https://github.com/timholy/Revise.jl"));
+                           Pkg.test("Revise")'
 
 after_success:
   - julia -e 'import Pkg; Pkg.add("Coverage"); using Coverage; Codecov.submit(Codecov.process_folder())'