Fixed a bunch of spelling.
Update paper.tex

A few changes in wording.
Merge pull request #55 from csu-hmc/spelling

Fixed a bunch of spelling.
Reworked intro with new citations, closes #36

- new bib file (includes some refs I have yet to cite, but maybe should)
- Different intro flavor in light of lack of gait data.
Note that Chester's data isn't available.
Added Sup2008 reference.