Fix README.md to display the *actual* TravisCI status.

The SVG button's image had never been updated to display the
actual master-branch build status! Now it's fixed.
Also, use https:// URLs.

README.md

@@ -1,8 +1,8 @@
 
-[![Build status](https://travis-ci.org/Quuxplusone/uthash.svg?branch=travis-ci)](https://travis-ci.org/troydhanson/uthash)
+[![Build status](https://api.travis-ci.org/troydhanson/uthash.svg?branch=master)](https://travis-ci.org/troydhanson/uthash)
 
 Documentation for uthash is available at:
 
-http://troydhanson.github.com/uthash/
+https://troydhanson.github.com/uthash/