Add "all" variants of commands

[thomastanck]

Depends on #191. Resolves #169.

Adds "all" variants such as addall, refreshall, archiveall, etc.

Summary of changes:

• Refactor DuplicateEntryCommandException to own class so it can be detected during addall operation
• Add addall and tests
• Add archiveall and tests
• Add tests for refresh
• Add refreshall and tests
• Add unarchiveall and tests

[coveralls]

Pull Request Test Coverage Report for Build 928

• 107 of 109 (98.17%) changed or added relevant lines in 14 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.3%) to 91.254%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/seedu/address/logic/commands/CommandResult.java	0	1	0.0%
src/main/java/seedu/address/logic/commands/RefreshAllEntriesCommand.java	21	22	95.45%
<!--	Total:	107	109	98.17%	-->

Totals
Change from base Build 927:	1.3%
Covered Lines:	2452
Relevant Lines:	2687

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💛 - Coveralls