MAINT: add runtests.py with enhanced feature set
DOC: update test rig instructions in HACKING
DOC: HACKING: don't recommend using virtualenvwrapper

The virtualenvwrapper cannot be installed via easy_install and has quite
many dependencies.
MAINT: update tox.ini
runtests: --verbose instead of --quieter
DOC: HACKING: pip instead of easy_install
Merge PR 2424 into master.

https://github.com/scipy/scipy/pull/2424