move source from my draft gist.

gist revision: https://gist.github.com/tonyseek/cc0f08d213dc5719406e/5bd50d9fbf0e1471b23abadbf84b1c8512e5c5b4
complement the docs of dinergate class.
complement the docs of the base pipeline property.
complement the docs of other pipeline properties.
add more description about "provide_value" implementation.
choice more sense names for pipeline properties classes.
rename pipeline.raw to pipeline.network
choice more sense name for RawHtmlProperty -> TextResponseProperty.
refine docs.
Merge pull request #4 from tonyseek/feature/dinergate-pipeline

Feature: the dinergate class and pipeline property (without test)