resolve #19 HTTP_X_FORWARDED_FOR が設定されている際のテストコードを追加

[keitakn]

issueURL

#19

やった事

HTTP_X_FORWARDED_FOR が設定されている場合でも正常に動く事を確認するテストコードを追加

[coveralls]

Pull Request Test Coverage Report for Build 46

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.436%

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Totals
Change from base Build 44:	0.0%
Covered Lines:	114
Relevant Lines:	117

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 48

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.6%) to 100.0%

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Totals
Change from base Build 44:	2.6%
Covered Lines:	117
Relevant Lines:	117

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💛 - Coveralls