Conduct case study with primary and secondary system

This issue is to conduct the case study with primary and secondary system.

The models are in obc/examples/case_study_4_fullHVAC, for instructions see the README.md file in https://github.com/lbl-srg/obc/tree/issue92_caseStudyFullHVAC/examples/case_study_4_fullHVAC

The development branch is issue92_caseStudyFullHVAC.

To do:

[x] Add VAV system model with building.
[x] Change the envelope model from the small office building to a floor of the medium office building.
[x] Correct heating supply temperature in idf file and reproduce sizing table, see https://github.com/lbl-srg/obc/issues/101#issuecomment-996871620 [Yan]
[x] #110
[x] Update to latest master of Buildings library (this will require updates to the controls as the master uses the revised version of CDL that refactors Add and some other blocks.
[x] Address comments on https://github.com/lbl-srg/obc/pull/104 [Karthik]
[x] Make SystemModel.BoilerPlant to pass regression tests. [Karthik]
[x] Add condensing boiler model [Michael]
[x] Remove sampling that happens every 1 second in SystemModel.BoilerPlant.Validation.System (as of commit ff90d65df90eb6ece0b388510165449c09b0c99c) [Karthik]
[x] Add boiler plant to SystemModel.BoilerPlant.
[ ] Add chiller plant to SystemModel.ChillerPlant.
[ ] Add heat loss of distribution pipes. Use 1/2 inch Armaflex for pipes, assume valves etc are insulated.
[ ] Add model that combines boiler plant, chiller plant and VAV system.
[ ] Add post-processing script.
[x] Size air-side system.
[ ] Size boiler plant.
[ ] Size chiller plant.
[ ] Make sure building static pressure is not higher than about 12 Pa. Otherwise add a relief fan.

lbl-srg / obc