fix($location): location html5Mode should not include filename in path

Previously, html5Mode would include the filename from the baseUrl (if present) as part of the path.
This was not a problem until url rewriting for html5 mode was enabled, in order to support relative
urls.

BREAKING CHANGE:

Previously, urls (in html5 mode) in the app would always be considered absolute paths within the app.
Now, they are relative unless prefixed with a forward slash or an absolute url containing a scheme
component.

Before:

     <a href="Book/Moby/ch/1" title="Moby: Ch1">Moby: Ch1</a>

Now:

     <a href="/Book/Moby/ch/1" title="Moby: Ch1">Moby: Ch1</a>

This breaking change would also apply to html5Mode in legacy browsers due to 3f04770