Source maps for jQuery 1.9.1.

This is essentially #836 for jQuery 1.9.1.

I downloaded the source map from the official jQuery site.
http://code.jquery.com/jquery-1.9.1.min.map

Then I replaced "jquery-1.9.1" with "jquery" in 2 places in the file.

Fortunately, jquery.min.js correctly points to jquery.min.map as its source map (search for //@ sourceMappingURL= to confirm) so I didn't have to modify it.