add travis

.travis.yml

@@ -0,0 +1,9 @@
+language: rust
+rust:
+- stable
+
+cache:
+- cargo
+
+script:
+- RUST_BACKTRACE=1 cargo test --all

README.md

@@ -1,4 +1,4 @@
-# poseidon-rs
+# poseidon-rs [![Build Status](https://travis-ci.org/arnaucube/poseidon-rs.svg?branch=master)](https://travis-ci.org/arnaucube/poseidon-rs)
 Poseidon hash implementation in Rust
 
 https://eprint.iacr.org/2019/458.pdf