Refined wording of the tour.
Tour wording: reacting to code review,

mentioned you need to login to work.
Only show activities tab for logged-in users.

Fixes #270.
Merge pull request #271 from egor83/270_activities_2

Only show activities tab for logged-in users.
Merge remote-tracking branch 'upstream/master'
Merge pull request #268 from egor83/master

Refined wording of the tour.
Fixed "Display name" field len,

fixed a typo in sanity check email.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master' into 275_field_len
Changed course homepage link to a button

(#274)
Merge pull request #277 from egor83/275_field_len

Fixed "Display name" field length
Merge remote-tracking branch 'upstream/master' into 274_course_page_link
Merge pull request #280 from egor83/274_course_page_link

Changed course homepage link to a button (fixes #274)
Merge remote-tracking branch 'upstream/master' into 202_flag_fb_exception