chore(travis): support for codecov.io

.travis.yml

@@ -63,3 +63,5 @@ script:
 after_success:
   # Report to coveralls
   - coveralls --build-root ${TRAVIS_BUILD_DIR} --include printf.cpp --gcov 'gcov-6' --gcov-options '\-lp'
+  ## Report to codecov
+  - bash <(curl -s https://codecov.io/bash)

README.md

@@ -1,7 +1,10 @@
 # printf / sprintf for embedded systems
 
 [![Build Status](https://travis-ci.org/mpaland/printf.svg?branch=master)](https://travis-ci.org/mpaland/printf)
+[![codecov](https://codecov.io/gh/mpaland/printf/branch/master/graph/badge.svg)](https://codecov.io/gh/mpaland/printf)
+<!---
 [![Coveralls Status](https://coveralls.io/repos/github/mpaland/printf/badge.svg?branch=master)](https://coveralls.io/github/mpaland/printf?branch=master)
+-->
 [![Coverity Status](https://img.shields.io/coverity/scan/14180.svg)](https://scan.coverity.com/projects/mpaland-printf)
 [![Github Issues](https://img.shields.io/github/issues/mpaland/printf.svg)](http://github.com/mpaland/printf/issues)
 [![Github Releases](https://img.shields.io/github/release/mpaland/printf.svg)](https://github.com/mpaland/printf/releases)