Remove unused usings.

Affect:

* src\Nest
* src\Profiling
* src\Serialization
* src\Tests
Merge branch 'develop' into feature/unused-usings

Conflicts:
	src/Nest/DSL/AnalyzeDescriptor.cs
	src/Nest/DSL/Bulk/BulkUpdateDescriptor.cs
	src/Nest/DSL/BulkDescriptor.cs
	src/Nest/DSL/ClearCacheDescriptor.cs
	src/Nest/DSL/ClearScrollDescriptor.cs
	src/Nest/DSL/CloseIndexDescriptor.cs
	src/Nest/DSL/ClusterHealthDescriptor.cs
	src/Nest/DSL/ClusterStateDescriptor.cs
	src/Nest/DSL/CreateIndexDescriptor.cs
	src/Nest/DSL/DeleteByQueryDescriptor.cs
	src/Nest/DSL/DeleteDescriptor.cs
	src/Nest/DSL/DeleteIndexDescriptor.cs
	src/Nest/DSL/DeleteMappingDescriptor.cs
	src/Nest/DSL/DeleteRepositoryDescriptor.cs
	src/Nest/DSL/DeleteSnapshotDescriptor.cs
	src/Nest/DSL/DeleteTemplateDescriptor.cs
	src/Nest/DSL/DeleteWarmerDescriptor.cs
	src/Nest/DSL/DocumentExistsDescriptor.cs
	src/Nest/DSL/FlushDescriptor.cs
	src/Nest/DSL/GetAliasesDescriptor.cs
	src/Nest/DSL/GetDescriptor.cs
	src/Nest/DSL/GetIndexSettingsDescriptor.cs
	src/Nest/DSL/GetMappingDescriptor.cs
	src/Nest/DSL/GetSnapshotDescriptor.cs
	src/Nest/DSL/GetTemplateDescriptor.cs
	src/Nest/DSL/GetWarmerDescriptor.cs
	src/Nest/DSL/IndexDescriptor.cs
	src/Nest/DSL/IndexExistsDescriptor.cs
	src/Nest/DSL/IndicesStatsDescriptor.cs
	src/Nest/DSL/IndicesStatusDescriptor.cs
	src/Nest/DSL/InfoDescriptor.cs
	src/Nest/DSL/MoreLikeThisDescriptor.cs
	src/Nest/DSL/MultiGet/SimpleGetDescriptor.cs
	src/Nest/DSL/MultiSearchDescriptor.cs
	src/Nest/DSL/NodesInfoDescriptor.cs
	src/Nest/DSL/NodesStatsDescriptor.cs
	src/Nest/DSL/OpenIndexDescriptor.cs
	src/Nest/DSL/OptimizeDescriptor.cs
	src/Nest/DSL/Paths/DocumentOptionalPathDescriptor.cs
	src/Nest/DSL/Paths/DocumentPathDescriptor.cs
	src/Nest/DSL/Paths/FixedIndexTypePathDescriptor.cs
	src/Nest/DSL/Paths/IndexOptionalPathDescriptor.cs
	src/Nest/DSL/Paths/IndexPathDescriptor.cs
	src/Nest/DSL/Paths/IndexTypePathDescriptor.cs
	src/Nest/DSL/Paths/IndexTypePathTypedDescriptor.cs
	src/Nest/DSL/Paths/IndicesOptionalExplicitAllPathDescriptor.cs
	src/Nest/DSL/Paths/IndicesOptionalPathDescriptor.cs
	src/Nest/DSL/Paths/IndicesOptionalTypesNamePathDecriptor.cs
	src/Nest/DSL/Paths/IndicesTypePathDescriptor.cs
	src/Nest/DSL/Paths/NodeIdOptionalDescriptor.cs
	src/Nest/DSL/Paths/QueryPathDescriptor.cs
	src/Nest/DSL/PercolateDescriptor.cs
	src/Nest/DSL/PutMappingDescriptor.cs
	src/Nest/DSL/PutWarmerDescriptor.cs
	src/Nest/DSL/RefreshDescriptor.cs
	src/Nest/DSL/RegisterPercolatorDescriptor.cs
	src/Nest/DSL/Reindex/ReindexDescriptor.cs
	src/Nest/DSL/ScrollDescriptor.cs
	src/Nest/DSL/SegmentsDescriptor.cs
	src/Nest/DSL/SourceDescriptor.cs
	src/Nest/DSL/SuggestDescriptor.cs
	src/Nest/DSL/UnregisterPercolatorDescriptor.cs
	src/Nest/DSL/UpdateDescriptor.cs
	src/Nest/DSL/UpdateSettingsDescriptor.cs
	src/Nest/Domain/Bulk/BaseBulkOperation.cs
	src/Nest/Domain/Responses/BaseResponse.cs
	src/Nest/ElasticClient-DeleteIndex.cs
	src/Nest/ElasticClient-DeleteMany.cs
	src/Nest/ElasticClient-IndicesStats.cs
	src/Nest/ElasticClient-MultiSearch.cs
	src/Nest/ElasticClient-Search.cs
	src/Nest/ElasticClient-State.cs
	src/Nest/ElasticClient.cs
	src/Nest/ExposedInternals/INestSerializer.cs
	src/Tests/Nest.Tests.Integration/Core/Get/GetMultiTests.cs
	src/Tests/Nest.Tests.Integration/Indices/AliasTests.cs
	src/Tests/Nest.Tests.Integration/RawCalls/HasUsefultServerExceptionTests.cs
	src/Tests/Nest.Tests.Integration/Reproduce/Reproduce654Tests.cs
	src/Tests/Nest.Tests.Integration/Reproduce/Reproduce659Tests.cs
	src/Tests/Nest.Tests.Unit/Core/Bulk/BulkTests.cs
	src/Tests/Nest.Tests.Unit/Search/InitializerSyntax/InitializerExample.cs
Merge branch 'develop' into feature/unused-usings

Conflicts:
	src/Nest/DSL/Facets/DateInterval.cs
	src/Nest/DSL/Query/MatchPhrasePrefixQueryDescriptor.cs
	src/Nest/Domain/Mapping/Descriptors/PropertiesDescriptor.cs
Merge branch 'develop' into feature/unused-usings
Reset all files to current develop.
Remove unused usings in NEST project.

Preserve these usings even if they are not used:

* System
* System.Collections.Generic
* System.Linq

Affect:

    src\Nest
    src\Profiling
    src\Serialization
    src\Tests

It doesn't affect src\CodeGeneration and src\Elasticsearch.Net because I'm not sure what code is generated and what isn't.
Merge branch 'develop' into feature/unused-usings
Merge branch 'develop' into feature/unused-usings
Merge pull request #758 from tkirill/feature/unused-usings

Remove unused usings.