Feat: Finished functionality

- Added test suite
- Added README.md

Create rust.yml for GitHubCI

tests/cli.rs

@@ -0,0 +1,18 @@
+use assert_cmd::Command;
+use predicates::prelude::*;
+
+#[test]
+fn dies_no_args() {
+    let mut cmd = Command::cargo_bin("echor").expect("cargo binary error");
+
+    cmd.assert()
+        .failure()
+        .stderr(predicate::str::contains("Usage"));
+}
+
+#[test]
+fn runs() {
+    let mut cmd = Command::cargo_bin("echor").expect("cargo binary error");
+
+    cmd.arg("hello").assert().success();
+}