Fix check Session createAt is not null or empty

[victorrattis]

• Check if session createAt is not null or empty;
• Convert to kotlin: Logger, AppLog;
• Add stack trace in error log message;

[coveralls]

Pull Request Test Coverage Report for Build 489

• 1 of 23 (4.35%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.09%) to 66.166%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
app/src/main/java/br/org/cesar/discordtime/stickysessions/data/remote/repository/SessionRemoteRepository.java	0	1	0.0%
app/src/main/java/br/org/cesar/discordtime/stickysessions/presentation/list/ListSessionsPresenter.java	1	2	50.0%
app/src/main/java/br/org/cesar/discordtime/stickysessions/presentation/lobby/LobbyPresenter.java	0	2	0.0%
app/src/main/java/br/org/cesar/discordtime/stickysessions/logger/AppLog.kt	0	18	0.0%
<!--	Total:	1	23	4.35%	-->

Totals
Change from base Build 484:	0.09%
Covered Lines:	485
Relevant Lines:	733

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💛 - Coveralls