First cut at Conanfile and Conan package test. (#50)

test_package/example.cpp

@@ -0,0 +1,15 @@
+#include <tl/expected.hpp>
+
+tl::expected<int, const char*> maybe_do_something(int i) {
+  if (i < 5) {
+    return 0;
+  } else {
+    return tl::make_unexpected("Uh oh");
+  }
+}
+
+int main(int argc, char** argv) {
+  (void)argv;
+
+  return maybe_do_something(0).value_or(-1);
+}