main content for mod2 close to being done for intro to R
broke ground on mod3 of intro to R
updates to conversion script -- still work to be done
swirl_out message when leaving swirl in 3 places in swirl.R: 2 in resume method and 1 in bye()

also replaced call to initial call to bye() in swirl()
 with call to removeTaskCallback so that exit msg in  bye wouldn't be printed
Roxygenized exported functions.
Resolve merge conflict in swirl.R

Merge remote-tracking branch 'gina/master'

Conflicts:
	R/swirl.R