job.js: Use $targetTable instead of querying the DOM again

@@ $targetTable = $( "table.swarm-results" )
JobPage: Hide non-functional reset buttons when not logged in

Initially this is set up correctly, but when refreshing the html
client-side, the user may have logged in (in a separate tab).

The HTML fetched from that point on would include reset buttons,
but they wouldn't be bound, and wouldn't work since the javascript
context still won't have SWARM.auth defined.

This ensures the buttons are only visible when the initial page
load had the user authenticated by removing the class inside the
SWARM.auth conditional.

If the user isn't logged in and later ajax updates add these
buttons, they will now remain hidden.