Merge pull request #3 from catherinev/pair-rickytux,catherinev

looks awesome team you guys
add created_at attribute that defaults to datetime now and make attr_reader and require date
Merge pull request #5 from catherinev/pair-kimpossibleg,monicadev

add created_at attribute that defaults to datetime now and make attr_rea...
Merge pull request #4 from catherinev/pair-rickytux,catherinev

add tests for complete/incomplete
there should actually be new tests this time...