Multiple loader issue on admin general setting page.

[bhaveshkhadodara]

When you select a new language from the general settings page and click submit multiple times, multiple loader images are appended.

Step 1: Open settings -> general page
Step 2: Select a new language from the site language option.
Step 3: click the "Save Changes" button multiple times.

[jariwalasagar]

Applied patch for this ticket.

[dilipbheda]

Updated patch to avoid selecting a second time same element.

[sabernhardt]

If the submit button (input) should be disabled, using .prop( 'disabled', true ) would be better than the .attr() method.
​https://api.jquery.com/prop/#entry-longdesc-1