Drop Emacs 23

- Enable lexical binding
- Use cl-lib instead of cl
Use process-file instead of call-process for remote execution
Merge pull request #37 from syohex/drop23

[WIP] Drop23
Add travis and MELPA badges
Update document for dropping Emacs 23 support
Fix Makefile for travis-ci and add .travis.yml
Bump up version and update Changes
Update MELPA links
specify onlu buffer name
Implement for eval-print command
Implement eval-print command of helm action
Fix error case when outputter is not default
Merge pull request #39 from syohex/improve-eval-and-print

Improve eval and print