Add margins to navbar buttons
Add margins to navbar buttons

When deploy_blocked Pulls and Ready Pulls exist as buttons in the navbar, they
don't have any spacing between them. This adds a small amount of spacing
between them so that they looked less smashed.

I'm open to creating another CSS class for the navbar buttons, but
`navbar-btn` seemed pretty specific to me.

iFixit/pulldasher,iFixit/pulldasher,iFixit/pulldasher,iFixit/pulldasher