Ignore Leiningen REPL history

If you open an REPL within your project with `lein repl`, your REPL history gets saved in .lein-repl-history. This file does not need to be committed to a repository

Leiningen.gitignore

@@ -4,3 +4,4 @@ pom.xml
 /classes/
 /targets/
 .lein-deps-sum
+.lein-repl-history