Issue 558: Data from private external tenants should not pop up in search results.
Issue 558: Filter out data in related content searches that originates from private tenants.
Data from private external tenants should not appear in related content searches.
Issue 562: The PP should be able to handle https-only tenants.
Issue 559: Validating the parameter sizes.

Created three validator methods:
 * isShortString()    -  Max 1.000 chars
 * isMediumString()   -  Max 10.000 chars
 * isLongString()     -  Max 100.000 chars

Added these size validations to all displayName, description and comment bodies.
Renaming RestContext.userId to RestContent.username
Avoiding race conditions in test-io by moving IO functions in the fs.stat callback
Merge branch 'issue-558-external-searches' of git://github.com/simong/Hilary into issue-558-external-searches
Documentation follow-up
Removed notEmpty check from isShortString-like validator methods and updated the error messages.
Added sanity checks in unit tests + documentation.
Merge pull request #559 from simong/issue-559-limit-parameter-length

Helenus acting up on large post in a discussion
Merge branch 'master' into issue-558-external-searches
Merge branch 'issue-558-external-searches' of git://github.com/simong/Hilary into issue-558-external-searches

Conflicts:
	node_modules/oae-content/lib/searches/relatedcontent.js
	node_modules/oae-search/lib/searches/general.js
Bumping activity TTL to 2 seconds in the TTL expiry test.
Issues 570 & 571: parameter validation on description and links
Issue 572: Administrators are considered members and managers of groups.
Fix copy/paste, minor cleanup
Merge pull request #567 from simong/fs.stat

Avoiding race conditions in test-io by moving IO functions in the fs.stat callback
Check for global admin as well + docs addition