This commit updates Bootstrap from 2.1.1 to 3.3.4. As it's a jump to a new
major version with backward incompatible changes, a lot of adjustments have
been necessary.
Beside the necessary adjustments resulting from the update, I did the following
additional ones to improve the experience with binder:
* As Bootstrap 3 is mobile first, a responsive design hassn't been that hard,
so I implemented that. I'm pretty sure it's not perfect yet, but a major step
into the right direction. As part of making binder responsive I moved the
menu to the top to take up less space on mobile devices.
* Improved vizualization of errors in forms, with highlighted form fields, which
contain the invalid data.
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