update contributors

Add all known contributors to date.
Merge branch 'master' into jarvis
Revision of the Getting Started lab.
Another sleight change to the Getting Started lab.
A revision ov the Arrays lab. Added a section on transposes and different
sorts of reshaping.
A few more edits to the arrays lab
Merge branch 'master' into typofixes
Further revision of the arrays lab
Added a little more to the arrays lab and cleaned up another typo.
Another small change to the arrays lab.
Added a short bit on ufuncs to the arrays lab.
Sleight wording change in arrays lab.
Swapped out main problem in the Arrays lab.
edits and small fixes

Fix spelling and some minor grammar.
small corrections and fixes
cannot find source for extensibility with C++
more minor fixes
Merge pull request #11 from ayr0/arrayprobs

corrections and fixes
Revised solutions for Arrays lab
Typo fixes in Arrays lab and redid array_solutions.py