Update 2014-04-01-programming-languages.md

Added some references for C.
Update 2014-09-01-teaching-assistant.md

Added information about being a graduate TA
Update 2014-09-01-teaching-assistant.md

Reformatted and rewrote slightly.
Update 2014-09-01-teaching-assistant.md

Made another formatting fix because I accidentally the whole markdown
Update 2014-09-01-teaching-assistant.md

Another minor formatting change.
Merge pull request #13 from NattyBumppo/gh-pages

Update 2014-04-01-programming-languages.md