Use kcov again

Because tarpaulin currently doesn't rapport accurate coverage

.travis.yml

@@ -7,19 +7,29 @@ cache:
   - apt
   - cargo
 
+# Dependencies of kcov, used by coverage
 addons:
   apt:
     packages:
-      - libssl-dev
+      - libcurl4-openssl-dev
+      - libelf-dev
+      - libdw-dev
+      - binutils-dev
+      - cmake
+    sources:
+      - kalakris-cmake
 
 rust:
   - nightly
 
+before_script:
+  - export PATH=$HOME/.cargo/bin:$PATH
+  - cargo install cargo-travis || echo "cargo-travis already installed"
+
 script:
-- cargo clean
-- cargo build
-- cargo test
+  - |
+      cargo build &&
+      cargo test
 
-after_success: |
-  cargo install --git https://github.com/xd009642/tarpaulin --force --branch develop cargo-tarpaulin
-  cargo tarpaulin --ignore-tests --exclude-files bin/* --ciserver travis-ci --coveralls $TRAVIS_JOB_ID
+after_success:
+  - cargo coveralls --exclude-pattern src/bin/,target/,tests/