an unregistered student can now view/submit feedback sessions for open session
student can now view results of a feedback session
now emails include the links to the unregistered actions
ported login filter to action level check
Merge branch 'dev' into 74749654

Conflicts:
	src/main/java/teammates/logic/core/Emails.java
basic infrastructure in place for not loggedin and unregistered access to pages
Merge branch 'rc' into 74749654
all tests that need to be fixed have been fixed
StudentCourseJoinAction is functional
logout page gives hint
confirmation page redirects properly
Merge branch 'dev' into 74749654
moved CourseJoinLink creation to StudentAttributes
components test passes
Modified instructor help page to remove info on evaluations and add info on feedback sessions
remove some actions
Tests submission of feedback session by unreg student
Merge branch 'dev' into 74749654
Add skeleton for question types
changed emails that are sent to students
Merge branch 'dev' into 74749654

Conflicts:
	src/test/java/teammates/test/cases/logic/StudentsLogicTest.java