Use topology from database when initialize te manager

[congwang09]

Resolves: #308

When initializing TE manager, we read from DB, if topology already exists, then use the one from DB. Also did some updates to use domain_name as key when saving to DB (in earlier case, we used LC-X for easy iteration of domains).

[coveralls]

Pull Request Test Coverage Report for Build 11130364476

Details

• 3 of 9 (33.33%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 58.396%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sdx_controller/handlers/lc_message_handler.py	0	2	0.0%
sdx_controller/messaging/rpc_queue_consumer.py	0	4	0.0%

Files with Coverage Reduction	New Missed Lines	%
sdx_controller/handlers/lc_message_handler.py	1	24.0%

Totals
Change from base Build 10951736194:	0.1%
Covered Lines:	1086
Relevant Lines:	1917

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💛 - Coveralls