fix(bootstrap): removed styles breaking responsiveness for high-res screens

Styles breaking responsiveness for higher resolution screens removed (in Bootstrap-only) and `things` convinced to be a little bit more responsive: now arrange in 1, 2, 3 or 4 columns depending on available space.

#### Before:
![before](https://docs.google.com/uc?export=view&id=0B9AF4Qo2eAu0ZU9QX0dXM1RDTW8)

#### After:
![after](https://docs.google.com/uc?export=view&id=0B9AF4Qo2eAu0LURqTXoyaXJoQUU)