Support annotations for ObjectProperties' fields

[snripa]

Currently the way you define the ObjectProperty is to provide some binding map that binds field names to property keys.

Along with this approach we can support some annotation based approach, like:

class ConfigPropPojo{
    @ConfigKey("org.proj.alias")
    String alias;
    @ConfigKey("org.proj.timeout")
    Integer timeout;
}

[antonkharenko]

@snripa I was thinking either we can reuse some existing JDK annotations for this purpose instead of adding new?