Refactor ngx-chat-messages to use flexbox instead of float

[trampi]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 302

• 3 of 18 (16.67%) changed or added relevant lines in 8 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 37.202%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
projects/pazznetwork/ngx-chat/src/lib/components/chat-message-list/chat-message-list.component.ts	0	1	0.0%
projects/pazznetwork/ngx-chat/src/lib/components/roster-list/roster-list.component.ts	0	1	0.0%
projects/pazznetwork/ngx-chat/src/lib/services/adapters/xmpp/plugins/publish-subscribe.plugin.ts	0	1	0.0%
projects/pazznetwork/ngx-chat/src/lib/components/chat-message-simple/chat-message-simple.component.ts	1	4	25.0%
projects/pazznetwork/ngx-chat/src/lib/components/chat.component.ts	0	4	0.0%
projects/pazznetwork/ngx-chat/src/lib/components/chat-message/chat-message.component.ts	0	5	0.0%

Totals
Change from base Build 294:	-0.1%
Covered Lines:	592
Relevant Lines:	1535

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💛 - Coveralls

[CodeBast4rd]

I see no problem with the changes.