Separate test from code to fix evaluation code

I permitted myself to propose this to you.

Also, added a makefile to hide the command's complexity (and use it inside the .travis.yml).

Tests are still ok.
```sh
# tony at dagobah in ~/repo/perso/org-toc on git:master x [11:22:14]
$ make test
emacs -batch -l ert -l *.el -f ert-run-tests-batch-and-exit
Running 3 tests (2014-11-01 11:25:06+0100)
passed  1/3  org-toc-test-flush-subheadings
passed  2/3  org-toc-test-hrefify-gh
passed  3/3  org-toc-test-hrefify-toc

Ran 3 tests, 3 results as expected (2014-11-01 11:25:06+0100)
```