Fix test mean for numpy
Merge branch 'master' of github.com:UCL/ucl_software_carpentry
Added link to mac version of firefox 19.0
Merge branch 'master' of https://github.com/UCL/ucl_software_carpentry
Update sql.md
Adding file that summarises positive and negative points from end of workshop
Merge pull request #15 from tompollard/master

+ve and -ve feedback from students