Merge pull request #13 from ChrisBoesch/master

up to date
url generation for challenge back end logic
Merge pull request #225 from ruijunhuang2010/master

up to date
url generation to play challenge game html part
Merge pull request #226 from ruijunhuang2010/master

url generation to play challenge game html part
minor change to add path ID parameter for badge challenge
Merge pull request #227 from ruijunhuang2010/master

minor change to add path ID parameter for badge challenge
Merge pull request #14 from ChrisBoesch/master

update
separate tag with comma
Merge pull request #228 from ruijunhuang2010/master

update
minor change
resolve feedback redirect issue
Merge pull request #229 from ruijunhuang2010/master

update
Merge pull request #6 from ChrisBoesch/master

update