Fixes: U4-2294 6.1.0: umbracoServer table can't be created on MySQL <5.6.5
Adds ability to use the query builder with string matches based on an NText column
Updates IMemberService with methods to search on string properties with an option to define how to match the string property, adds all supporting unit tests.
moves classes into sep files
Merge remote-tracking branch 'origin/6.2.0' into 7.0.2

Conflicts:
	src/Umbraco.Core/Persistence/Querying/BaseExpressionHelper.cs
	src/Umbraco.Core/Persistence/Repositories/MemberRepository.cs
	src/Umbraco.Core/Services/IMemberService.cs
	src/Umbraco.Core/Services/MemberService.cs
	src/Umbraco.Core/Umbraco.Core.csproj
fixed merge issues