_compute_redirect_to_location signature is changing

the method shouldn't be private because the superclass method isn't
private.  Also we don't need alias method chain, we can just call super.
Maintain backwards compatibility with Rails <4.2
v2.2.3
Wait to change the URL until after the response has been received. Fix #353
v2.3.0
Include check for nil-session
Merge pull request #400 from 545ch4/master

Include check for nil-session
Clone the link so attributes are not altered - Fix #399
Clarify page:update description in README - Fix #398
Move cloning of link element inside the Link class to preserve ability to inspect surrounding elements
Add page:before-unload event - Close #401
Add Prototype compatibility with custom events - Fix #384
Maintain load order of scripts in the body - Fix #389
Provide target URL to page:before-change event - Close #357
Move event names into Turbolinks.EVENTS
expose event list via `Turbolinks.events()`

refs #403
Ignore empty hash links when the current location ends in an empty hash - Fix #407
Check if Content-Type header exists before checking its value - Fix #410
Handle HTML parsing bug in Safari 7.1 - Fix #408
Properly ignore empty hash links - Fix #407 again