don't force nav-list items to be too wide

The natural width of navlist items (with bootstrap 3) should be the parent's
width minus its padding.  Inheriting the width from the parent means the
padding isn't accounted for, making the width too large and breaking the
positioning of right aligned items.
reword subscribe link to be shorter and with better grammar

Shortening this link prevents it from wrapping.
Merge pull request #1279 from haarg/nav-width

Fix nav-list item width