Bootstrap 3.4.0 released

[fabpacheco]

Since Master Bootstrap latest version uses Booststrap 3.3.7, just letting you know that version 3.4 was released december 13 2018 mostly fixing some XSS issues.

See the ship list in twbs/bootstrap#27288
Download page: https://getbootstrap.com/docs/3.4/getting-started

[gsuez]

Thank you @fabpacheco