Install command typo.

Package Manager Console install command typo fixed.
Dont sent TypeNameMarker  as type, convert to type-strings
fix #907 using untyped SearchRequest() should still infer default index
Fix MultiSearchRequest test to account for #907
Adding nullcheck and use Self.Types
Add more unit-tests for IndicesStats
Remove duplicated code
Renamed parameter to types instead of completion_fields
Filename corrections of cluster put/get settings responses