Support for multiple exclusion strategies

[Narretz]

This has been discussed in schmittjoh/JMSSerializerBundle#140, but it mainly belongs here now.

My personal use case for multiple exclusion strategies: I'd like to use Groups with the proposed DepthExclusion strategy (#4). Restrict the properties that are serialized, and restrict the depth to which some properties are serialized. I need both for that. Strategies really complement each other; the same is true for e.g. groups and version.

The issue mainly dealed with three changes:

1. Adding a serializer builder service that separates the new settings for each invocation => Builder exists
2. The option to configure specific serializers in the config files => would go to SerializerBundle
3. Changes to Groups => Default Groups are there, I think that was it
4. A new option to have a chain of exclusion strategies instead of a single one

Is there still demand for this?
Looks like the builder doesn't have support for setting (multiple) exclusion strategies yet. So it looks like we'd need to do that and 4.). Or has this been accomplished some other way?

[Narretz]

Okay, I tried to rebase Seldaek's latest commits (just 5 months old) onto master, but it doesn't play well with the current builder. I assume you could add public methods to the builder similar to configureEventHandlers, addMetadataDirs etc. that set the exclusion strategies. Not sure if you would still need to add some sort of ChainExclusionStrategy, though.