Allow any any options for connections in Configuration

Changed VariableNode to prototyped ArrayNode

Listing all options for connection in Configuration

Removed \MongoClient consts

Changed readPreferenceTags to arrayNode
Added full XML configuration and adjusted everything for it to pass
Fix Connection option config parsing

Also refactors the ConfigurationTest class. Removed strict checking of default_commit_options (and tests), added missing options. Fixed handling of readPreferenceTags option for XML.

As a change, "server" and "options" no longer have default values; however, existing code in Configuration should handle this fine.
Clean up XML and YML config fixtures
Use boolean config type for "auto_mapping" option
Update XSD to match Configuration class
Do not skip tests if mongod, PECL driver, or ODM is unavailable
Fix name of "annotation" mapping driver in tests and docs
Test profiler options in full configurations
Handle "metadata_cache_driver" namespace option

This is currently supported in AbstractDoctrineExtension.
Only prepare "metadata_cache_driver" string values before normalization
Merge pull request #219 from doctrine/3.0-ctor-args

Update configuration for 1.4.x driver options