algerbraic_connecitivity tests are not skipped for scipy < 0.12

It seems that the low level functions in `scipy.linalg.blas` used in `algebraic_connectivity` were added at scipy 0.12:

http://docs.scipy.org/doc/scipy/reference/linalg.blas.html

At work I'm using Debian stable which ships with `scipy` 0.10, the tests for `algebraic_connectivity` throw errors in this context (eg `AttributeError: 'module' object has no attribute 'algebraic_connectivity'`). I guess that scipy is detected, and thus test are not skipped, but functions are not imported in the namespace because `from scipy.linalg.blas import (dasum, daxpy, ddot)` fails.