Add support for NodesHotThreads

Closes #508.
Smarter format recognition when parsing nodes.hot_threads response
Bulk-operation without index/type

Bulk-operations is not working if elasticsearch settings
rest.action.multi.allow_explicit_index
re #880 - Ensures that a nested filter consisting of only a filter does not result in a conditionless NEST filter (leading to its exclusion from generated json query)
Update tests for bulk-update with FixedPath to work if even if the _index attribute not are allowed
Update tests for multiperculate with FixedPath to work if even if the _index attribute not are allowed
Update tests for multisearch with FixedPath to work if even if the _index attribute not are allowed
Update tests forMultiSearch with FixedPath to work if even if the index attribute not are allowed
Update serializer for Bulk, MultiSearch and MultiPercolate to ignore index-parameter if that is the same as FixedPath
Correcting BulkIndexDetailsFixedPath test
added the an offsets option for IndexOptions without it users can not use the postings highlighter see issue 891
Merge pull request #881 from Philo/develop

re #880 - Ensures that a nested filter consisting of only a filter does ...
Add support for span multi term query.

Closes #863.
Install command typo.

Package Manager Console install command typo fixed.
fix #866 default disable proxy detection to false, either way the boolean is set can introduce an initial delay based on the users OS/network/proxy settings. This way atleast no special setting is necessary to introduce fiddler to listen to NESTs requests
Merge pull request #896 from elasticsearch/feature/span-multi-term

Add support for span multi term query.
Merge branch 'issue-870' of github.com:Tasteful/elasticsearch-net into Tasteful-issue-870

Conflicts:
	src/Tests/Nest.Tests.Integration/Core/Bulk/BulkUpdateTests.cs
Fix Count() executing a POST without request body

Logic was reversed when determining whether to execute a POST or GET
request.  If there's no source param, then it should be a GET, otherwise
POST.

Closes #898.
reverted @Tasteful fixes to tests so they work with rest.action.multi.allow_explicit_index set to false, nest tests should serve as documentation for vanilla elasticsearch installs otherwise FixedIndex() might be taken for mandatory
Merge branch 'develop' of github.com:elasticsearch/elasticsearch-net into develop