some minor changes to test performance improvements
Added cast method
Added test to the correct place.
performance  improvements.
Merge branch 'develop' into feature/performance

Conflicts:
	Source/Glass.Mapper.Sc/GlassHtml.cs
centralised SitecoreContext creation to improve performance
Merge branch 'feature/performance' into develop
Merge branch 'develop' of github.com:mikeedwards83/Glass.Mapper into develop

Conflicts:
	Source/Glass.Mapper/Pipelines/ObjectConstruction/Tasks/CreateConcrete/CreateConcreteTask.cs
Merge remote-tracking branch 'origin/feature/cast' into develop