This is the first of two changes. This replaces the simple function used as a factory for the chain of channels used to process requests at runtime with a proper class capable, also, of manipulating the chain at runtime. Thus ChannelManager :)

Here's why that is useful.

1) We can lazily install the EventPublishingChannel when someone access the event target from ServiceTracker.

2) We can interact with the concrete classes in the chain. This will let us add simple hit-filtering support to the public tracker interface (which in turn will call through to the chain to install the filter at runtime).

3) Make Oren's fancy auto label generating code available on the Chromalytics git repo.

4) We can replace EventPublishingChannel with one of the fancy new filter. Actually we should just deprecate the EventTarget stuff entirely as folks can install filters to listen for hits.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71206987
Rebuild google-analytics-bundle.js
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71686089
Make ParameterMap public so that it can be used by filters (which will arrive in a subsequent CL).
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71690262
Add support for client supplied hit filters.
Deprecate support for EventTarget.
Nuke EventPublishingChannel, reimplement using a filter (but still totally deprecated).
Share a single settings object across all service instances & trackers which I believe is more correct than what we were doing.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71781456
Fix an issue in ServiceChannelManager where function wasn't correctly scoped.
Add a test.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71877918
Add ParameterMap and new Filter symbols to the export symbols setup.
Eliminate EventHandler code from example apps.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=72101287
Nuke EventTarget code entirely.
Update 1st-party apps to use filter in place of EventTarget code.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=72183180
Bump the library version to 1.5.0.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=72421279