Use codecov

I think jump-dev uses codecov and not coveralls; either way, coveralls is not working and codecov seems to.

Author: ericphanson

.travis.yml

@@ -1,4 +1,5 @@
 language: julia
+codecov: true
 os:
   - linux
   - osx
@@ -7,8 +8,6 @@ julia:
   - 1.4
 notifications:
   email: false
-after_success:
-  - julia -e 'using Pkg; Pkg.add("Coverage"); using Coverage; Coveralls.submit(process_folder())'
 jobs:
   include:
     - name: "Benchmark"