remove commented out admin form styles

These should all be covered by the recent changes in forms.less
which is the appropriate place for them anyway.

Also deleted the border on the device detect regex table since
it was right next to them and I just saw that my change to fix the
underlying problem was just integrated in 2.6 and master.
using media queries to limit input width

Just for discussion, the 500px value was chosen mostly at random,
so give others a try.
tempfix
merged #132
Merge branch 'master' of github.com:bmbrands/theme_bootstrap