Ipv4 RangeAggregation behaves like other ranges

Added Ip4ExpressionRange
Updated Ip4RangeAggregationDescriptor to take params
Func<Ip4ExpressionRange, Ip4ExpressionRange>[] ranges
Updated integration tests
Added back old style of doing Ipv4 Ranges

Added back old style of doing Ipv4 Ranges marked as obsolete.
Added unit test for string array in Ipv4 Ranges
Moved new IpRangeString Agg test to correct loc
Merge branch 'ipv4range-fix' of https://github.com/andersosthus/elasticsearch-net into andersosthus-ipv4range-fix
Merge branch 'andersosthus-ipv4range-fix' into 2.0
Remove obsolete Ipv4 agg string method