New cache driver definition for Doctrine running in non-dev mode and cache driver is not set.

This cache driver was added with doctrine/common#109
Fixed CS
In some weird situation the SimpleXmlIterator used to iterate on the ``$xmlRoot->field`` property just get resetted. This solution avoid this situation. This problem occurs when Symfony2 warms up cache with autogenerate proxy to ``true``
simplified __call method
Fixing a bug when calling setDiscriminatorMap from multiple sources (ie: from Events::loadClassMetadata and annotation).
Added test coverage for repository functions when using filters
[DDC-1766] Initial implementation of hydration cache.
[DDC-1766] Rename closure
[DDC-1766] Remove some testcode
[DDC-1766] Add test with explicit cache key.
[DDC-1766] Add usage of default result cache driver, add more docs.
[DDC-1766] Explain details of Hydration cache, introduce AbstractQuery#setResultCacheProfile method
[DDC-1766] Cleaned up code.
[DDC-1766] More cleanups
improved exception message
DDC-1757 test and patched query builder
Parameter PHP documentation for the QueryBuilder::getRootAlias() method
[DDC-1766] Rewrite getHydrationCacheId() to use existing processParameterValue() method. Other code style changes.
Merge pull request #329 from doctrine/DDC-1766

[DDC-1766] Initial implementation of hydration cache.
Merge pull request #321 from import/feature/newCacheDriver

Addition for new cache driver