兼容Python3的输出

[yalechen-cyw3]

在python3.7下会出现以下问题

Python3下异常

故设置，当python3时候，将message由bytes类型解码为str类型

[coveralls]

Pull Request Test Coverage Report for Build 496

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 145 unchanged lines in 7 files lost coverage.
• Overall coverage decreased (-0.2%) to 40.946%

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Files with Coverage Reduction	New Missed Lines	%
cobra/init.py	1	26.19%
cobra/templite.py	1	0.0%
cobra/config.py	2	56.32%
cobra/log.py	3	45.0%
cobra/api.py	4	12.47%
cobra/cve.py	8	80.18%
cobra/utils.py	126	31.65%

Totals
Change from base Build 489:	-0.2%
Covered Lines:	1696
Relevant Lines:	4142

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 490

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 18 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+0.03%) to 41.171%

---

Files with Coverage Reduction	New Missed Lines	%
cobra/init.py	1	26.19%
cobra/templite.py	1	0.0%
cobra/log.py	1	45.0%
cobra/utils.py	1	33.33%
cobra/config.py	2	56.32%
cobra/api.py	4	12.47%
cobra/cve.py	8	80.18%

Totals
Change from base Build 489:	0.03%
Covered Lines:	1695
Relevant Lines:	4117

---

💛 - Coveralls