Travis CI enablement

- Added test_requirements, test harness, and travis changes
- Made tempfile context manager importable
- Made context manager remeber it's current directory and return to it
Merge pull request #6 from mitocw/cg/enable_travis

Travis CI enablement
Correct Travis Deps
Switching to conda install of scipy
Add coveralls
Merge pull request #7 from mitocw/cg/fix_travis

Fixes to Travis Build
Added ToC referencing capabilities in main.py, render/edXpsl.zpts, plastexpy/edXpsl.py with supporting macros
Added the modified edXpsl.sty files for compiling course to PDF, located in the \texinput folder
Added a deleted comment to edXpsl.py file noting that edXsections become edXsequentials
Added documentation entries for toclabel and tocref, and modified some content for edXvideo and edXdiscussion
Modified main.py to prevent the TOC routine if running section_only, and removed duplicate lines from edXpsl.py