Less update

Unpin less (2.0 works great)
And use variable for celltoolbar border  radius.
which is what I do: 

```
 ipython
Python 3.4.2rc1+ (default, Oct  1 2014, 11:58:57)
Type "copyright", "credits" or "license" for more information.

IPython 3.0.0-dev -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: if None and i_dont_exist():
   ...:     print('cannot get there')
   ...:

In [2]: if True and i_will_crash():
   ...:     print('will not get there either')
   ...:
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-2-bcf69554df8c> in <module>()
----> 1 if True and i_will_crash():
      2     print('will not get there either')
      3

NameError: name 'i_will_crash' is not defined
```