Fix certain documentation urls not opening on OS X.

For an example of a url that wouldn't load, see the cider-doc view for Integer/parseInt.
(browse-url "http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String, int)")
does not work on OS X. Emacs issues the command
```
open 'http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String, int)'
```
which does not work correctly: you are sent to http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html%23parseInt(java.lang.String,%20int)

Url-encoding the input to browse-url fixes this.

I'm sure about the change to the javadoc button.
I'm sure about the change to cider-docview-javadoc.
I'm not sure about the change to the url button, since I don't know how to find
documentation for which this button actually gets created.

I have not tested this on any platform except OS X.