adding theory manual. this is a template and index for adding entries; modified site index to build this as developmental.
added a references section.
added a references section and an example of how to add math.
fixed a typo in models.rst api
fixed grammar error in enrichment description.
fixed more grammar errors in enrichment description.
fixed grammar error in enrichment description.
fixed some typos at top of stl containers api.
fixed typo in cli api index.
fixed another that/which error, this one in rxdata.py.
added a caveat directing people to look up manuals of items not implemented natively in pyne.
added template files for each of the items that seem like they should have theory sections. Updated the indext to include these, but not the base template.
Merge branch 'staging' of github.com:pyne/pyne into staging
Merge pull request #425 from rachelslaybaugh/staging

adding theory manual in response to #334