Test using ecukes and Travis CI setup

To run in Emacs, I geuss you can do that in the following steps:

1. Install Ecukes
2. Go to the project root of smartparens (e.g., open smartparens.el).
3. `M-x ecukes RET`.

As ecukes test is usually very stateful, I think it is better to do the test in separated Emacs process, otherwise it alters your smartparens setting.

If you are in unix-like system, just run `make`.

I also added travis-ci setup, you just have to go to https://travis-ci.org/profile and flick the switch.