Clean up the response materializer classes.
Add fields overload to QueryString method to specify field patterns.
Add support for string .Contains and .StartsWith mapping to query_string.
Stop FacetExpressionVisitor visiting so much of the expression tree.
Do not allow .StartsWith, .Contains or .EndsWith inside .Where - must go in .Query. Also add support for EndsWith.
Merge branch 'dev' of https://github.com/CenturyLinkCloud/ElasticLINQ into dev
Merge branch 'dev' of https://github.com/ethaler/ElasticLINQ into dev
Revert "Merge branch 'dev' of https://github.com/ethaler/ElasticLINQ into dev"

This reverts commit c6b655b771f55f130b8ba1ad8392b8ed55db25a5, reversing
changes made to e520a4ae41c80924ba4f71e944a83764cba9ef73.