Merge develop to master for new release

fix for PHP 5.3

Merging develop to master for new release

#474 - Using GET method when extracting remote file with stream.uri

Add Guzzle 6 Adapter implementation

Fix document syntax

Remove duplicated word

 Add Guzzle3 Client Adapter

usleep after curl_multi_select -1

Enable Simple Group Format

Correct language about RealtimeGet query use

According to these php bugs:

* https://bugs.php.net/bug.php?id=61141
* https://bugs.php.net/bug.php?id=63842

thats what we should do.

I came across this issue when trying to make the ParallelExecution
working on my CentOS 7.3 box. It spinlooped inside the changed loop.

Also guzzle is doing the same thing:

https://github.com/guzzle/guzzle/blob/master/src/Handler/CurlMultiHandler.php#L103

I am not sure if the timeout needs to be configurable and if the choosen
value (100) is good.

Update plugins.md

small fix for non-working external links ("wikilink")

Creating new release

Add support for comma-separated values in conversion to array

add spatial component

add basic support for nested documents

rename method

don't always pass xml string as parameter (too expensive with long documents)

Allows key and exclude for interval facet