Add Travis CI and update tests. Start a Changelog.

* .travis.yml: new file

* README.mdown: Add Travis CI badge.

* Rakefile: use ert-run-tests-batch-and-exit.

* yasnippet-tests.el (example-for-issue-404-external-emacs): Use
`yas-with-snippet-dirs' to not depend on bundled snippets.
(yas--call-with-temporary-redefinitions): Use `cl-labels' since no
cl-flet in emacs-24.3's cl-lib.el.
(loading-with-cyclic-parenthood): prog-mode doesn't exist in emacs
24.3.
(yas-batch-run-tests): remove it.

* yasnippet.el (require): require cl-lib during byte-compilation
and load.

Rakefile

@@ -16,9 +16,8 @@ FileUtils.mkdir_p('pkg')
 
 desc "run tests in batch mode"
 task :tests do
-  batch_run_line = "(yas-batch-run-tests t)"
-  sh "#{$EMACS} -Q -L . -l yasnippet-tests.el -nw" +
-    " --batch --eval '#{batch_run_line}'"
+  sh "#{$EMACS} -Q -L . -l yasnippet-tests.el" +
+    " --batch -f ert-run-tests-batch-and-exit"
 end
 
 desc "create a release package"