Fix border-radius on left&right aligned stacked nav-tabs

[wyrd-code]

.nav-tabs.nav-stacked had first and last tabs border-radius adapted only for regular tabs. Left & right aligned stacked tabs weren't taken into account.

[travisbot]

This pull request passes (merged 89fc58d into 857b8fb).

[fat]

Hey @tomoglavas,

Thanks for opening this pull-request! Unfotunately, it looks like it fails to pass the tests neccessary for submitting to bootstrap. The following tests are currently failing:

• should always be made against -wip branches

For a full list of issue filing guidelines, please refer to the bootstrap issue filing guidelines.

thanks!