Merge pull request #1 from Gimperion/master

R PostgreSQL integration
stub out powerpoint
Merge remote-tracking branch 'origin'
build in more extras
README.md
add links
yet more links
link to SQL joins ref
link to Eric's json-to-csv
two more data sources
add csvkit!
move Tidy Data to 11
starting to get labs linked
link up some psql love
first pass at SQL lab
add ref to database source
move link to json-to-csv
fix link in md
phrasing
punctuation