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
Merge with latest master from upstream. Fix merge conflict with Leiningen.gitignore
Merge pull request #623 from seabre/patch-1

Ignore Leiningen REPL history