bug fixed
Merge pull request #2 from alexshotime/master

added foo
added day1 keynote
removed testing file foo
Calculator project
Added w1 d2 keynote
Merge pull request #3 from TechFounder/master

Here's the Calculator program you requested
added w1 d3 keynote
Add group_assign_app
Merge pull request #4 from bartolotta/master

Added the Assign Student Groups app
added exercises for array and hash
added twitter handles
added subway solution
Merging from Zhao's