HLD: Azure/SONiC#646
In modular chassis, add CHASSIS_STATE_DB on control card
Why I did it
Modular Chassis has control-cards, line-cards and fabric-cards along with other peripherals. Control-Card CHASSIS_STATE_DB will be the central DB to maintain any state information of cards that is accessible to control-card/
How I did it
Adding another DB on an existing REDIS instance running on port 6380.
**- Why I did it**
Align style with slightly modified PEP8 standards (extend maximum line length to 120 chars). This will also help in the transition to Python 3, where it is more strict about whitespace, plus it helps unify style among the SONiC codebase. Will tackle other directories in separate PRs.
**- How I did it**
Using `autopep8 --in-place --max-line-length 120` and some manual tweaks.
bring up chassisdb service on sonic switch according to the design in
Distributed Forwarding in VoQ Arch HLD
Signed-off-by: Honggang Xu <hxu@arista.com>
**- Why I did it**
To bring up new ChassisDB service in sonic as designed in ['Distributed forwarding in a VOQ architecture HLD' ](90c1289eaf/doc/chassis/architecture.md).
**- How I did it**
Implement the section 2.3.1 Global DB Organization of the VOQ architecture HLD.
**- How to verify it**
ChassisDB service won't start without chassisdb.conf file on the existing platforms.
ChassisDB service is accessible with global.conf file in the distributed arichitecture.
Signed-off-by: Honggang Xu <hxu@arista.com>
