added additional ctor for member to create an empty one
Merge remote-tracking branch 'origin/6.2.0' into 7.1.0

Conflicts:
	src/Umbraco.Core/Models/Member.cs
doh, fix for new ctor
Merge remote-tracking branch 'origin/6.2.0' into 7.1.0

Conflicts:
	src/Umbraco.Core/Models/Member.cs
fixes bug with col name
Merge remote-tracking branch 'origin/6.2.0' into 7.1.0

Conflicts:
	src/Umbraco.Core/Persistence/Repositories/MemberRepository.cs
Ensures we are not directly referencing Membership.Provider and instead targetting our provider by alias.