Update contents of module 1
quick typo fix in readme
Add BEM module, modify ketch's role.
Merge pull request #4 from numerical-mooc/phugoid_solution

Phugoid solution
ignore checkpoint
add downloadable copy of Ian Hawke's notes
Trivial typo.
Add a parametric solution plot with interaction for the phugoid solution.
Move style load to the bottom
Tweak style sheet
Rerun with my updated conda
enable equation numbers in MathJAX using javascript hack in CSS
rename pendulum notebook to phugoid flight
code showing oscillations in flight path due to vertical wind gust
Add more intro text, phugoid theory
Add equation numbers, fig. captions & polish text

To add equation number must enclose in an equation or eqnarray
environment
typo in equation
show phugoid oscillation from vertical gust
rename to phugoid oscillation
Merge remote-tracking branch 'refs/remotes/origin/phugoid_solution' into phugoid_solution