Retrieving default group joinable value from the admin config
Issue 543 - Hiding content and discussion libraries when the library owner has a non-public visibility.
#543 - Refactored resolveTargetLibraryVisibility into resolveTargetLibraryAccess

resolveTargetLibraryAccess now returns whether the current user has access to a library
and if he does, which library stream should be shown.
Removed JSON.stringify from error assertion.
Issue 551 - Returning 401 on group profiles that should be hidden and are not joinable.

Also added `canJoin` property.
Expanded the JSDocs on getFullGroupProfile as per @mrvisser's PR review.
Merged master into issue-543-library-leaking
Merge remote-tracking branch 'simong/issue-543-library-leaking'
Issue 557: Etherpad must be embedded on the same tenant host
Made some searches in the unit tests more unique.
Fixing else if alignment with brackets
Removed etherpad hostname from the README as it is no longer needed.
Merge pull request #551 from simong/issue-551-group-rest

Make the group REST api more inline with the other APIs + add a canJoin property to group profiles
Merge pull request #557 from simong/issue-557-etherpad-same-domain

Etherpad must be embedded on the same tenant host