add 'resolved' boolean field to topic data

[kaylalei]

resolved topic data field is initialized to false upon creation of a new topic and gets set to true when follow-up posts are made for that topic.
Fixes #2

[coveralls]

Pull Request Test Coverage Report for Build 10975561826

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.009%) to 81.833%

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Totals
Change from base Build 10949452674:	0.009%
Covered Lines:	22344
Relevant Lines:	25863

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💛 - Coveralls