Add missing m2eclipse life cycle mapping

Also, use ignore instead of execution because those plugins are not
really useful when building from Eclipse anyway.
Move generic code to HttpOrSpdyChooser to simplify implementations

Motivation:

HttpOrSpdyChooser can be simplified so the user not need to implement getProtocol(...) method.

Modification:

Add implementation for the method. The user can override it if necessary.

Result:

Easier usage of HttpOrSpdyChooser.
添加注释