Add accordion menus for vertical timeline events

[Xetnus]

Fixes #683 by adding an accordion menu for all linked DB items (e.g., commits, developers, filepaths) in the vertical timeline events.

Blocked by #707 and related PRs. Other projects (Struts, Chromium, and Tomcat) will need to be changed once those PRs are merged.

Currently, most (if not all) linked commits aren't in our database, so the links don't go anywhere. For every commit hash and developer name not found in our database, I indicate this by adding either "(Untracked)" or "Unidentified Developer", respectively.

Also a part of this fix:
VulnerabilityHistoryProject/httpd-vulnerabilities#101
VulnerabilityHistoryProject/vhp-writing#6

[coveralls]

Pull Request Test Coverage Report for Build 1031

• 2 of 30 (6.67%) changed or added relevant lines in 3 files are covered.
• 12 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-2.0%) to 86.637%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/event_generators/weekly_report_events.rb	0	28	0.0%

Files with Coverage Reduction	New Missed Lines	%
lib/event_generators/weekly_report_events.rb	3	20.72%
test/lib/event_generators/release_events_test.rb	4	66.67%
test/lib/event_generators/all_vulnerability_events_test.rb	5	68.75%

Totals
Change from base Build 1030:	-2.0%
Covered Lines:	1368
Relevant Lines:	1579

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💛 - Coveralls