Few UX refinements for presenting Updates

[snwh]

Pill to Show Update Count

I think it would be good to display the count for the number of updates available on the button once Bazaar has finished checking for updates

Spinner with Tooltip

Instead of displaying the spinner with the string inline on the header position it where the button would be and use a tooltip

Manual Refresh

Keeping a "Check for Updates" button always available in the header I think is a good idea, especially if/when automatic update checking is disabled.