add coverage

Author: jbrea

test/coverage/Project.toml

@@ -0,0 +1,2 @@
+[deps]
+Coverage = "a2441757-f6aa-5fb2-8edb-039e3f45d037"

test/coverage/coverage.jl

@@ -0,0 +1,9 @@
+# only push coverage from one bot
+get(ENV, "TRAVIS_OS_NAME", nothing)       == "linux" || exit(0)
+get(ENV, "TRAVIS_JULIA_VERSION", nothing) == "1.0"   || exit(0)
+
+using Coverage
+
+cd(joinpath(@__DIR__, "..", "..")) do
+    Codecov.submit(Codecov.process_folder())
+end