super quick performance win in the case where people don't pass in distinct values
Fixes: U4-5157 Membership.GetUser() causes 13 SQL queries, including duplicates
updates content xml bits so if it's called outside a web req it still executes.

Conflicts:
	src/Umbraco.Web/umbraco.presentation/content.cs
Fixes: U4-5199 Appending certain query strings to URLs cause InvalidOperationException (The UmbracoContext.Current is null)
Merge remote-tracking branch 'origin/6.2.2' into 7.1.5

Conflicts:
	src/Umbraco.Web/PublishedCache/MemberPublishedContent.cs
	src/Umbraco.Web/Security/MembershipHelper.cs
	src/Umbraco.Web/umbraco.presentation/content.cs