PHP-1030: Default GridFS chunk size default to 255K (from 256K)
Merge pull request #638
PHP-1022: Removed commandCursor in favour of aggregateCursor.

It now should stay on collection, next to aggregate. It does not support a
varargs pipeline.
Merged pull request #631
Added the connection hash that was used while running a command to its output.

We are adding this as a subitem of the $php key, as we can not rely on f.e.
"hash" to be added by the server at some point. Hence we namespace with $php.
It also adds this for *every* command to be consistent. Of course, right now,
it's going to be useful only for MongoCommandCursor::fromDocument, which is
coming in the follow up PR.
Merged pull request #635
Refactor cursor info gathering functions into one.
Add MongoCommandCursor::createFromDocument

This is the implementation for what we discussed during our meeting.
Merged pull request #636
PHP-972: Implement MongoCollection::parallelCollectionScan().

Mostly based on Hannes' code in
https://github.com/mongodb/mongo-php-driver/pull/629
Merged pull request #637
PHP-1039: Use dropIndexes command instead of deleteIndexes
Merge pull request #642
PHP-1035: New MongoDB::command() argument to collect server hash

The options array (second argument) may now be null, which is convenient if the user has no options but would still like to collect the server hash.
PHP-1035: Use command() hash arg instead of $php meta field
Additional tests for command() $options argument
Merge pull request #639
PHP-1033: Organize third-party code and license information.
Merged pull request #646
PHP-1038: Do not allocate zval to set command cursor batchSize