Add collapsed default class to navbar-toggle

BS3 commits: 44f83fff90fc7b12961f6d7bdb92a7e1b869c306
Fixes 14053: Don't show radio/checkbox in justified button groups

BS3 commits: 9be2bbb5efdc09eb5446719daa8ac892b93f2ede
Fixes 13835: More explicitly document mobile dropdown menu dismissing behavior

BS3 commits: 5e41a23ec5da02e67be2a67dd0c692517b3b01bd