optimize fish_logger and fish_common

[mindjun]

optimize fish_logger from issue #221;optimize fish_common from issue #222

[coveralls]

Pull Request Test Coverage Report for Build 500

• 10 of 15 (66.67%) changed or added relevant lines in 3 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.4%) to 89.281%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
fishbase/fish_logger.py	2	7	28.57%
<!--	Total:	10	15	66.67%	-->

Files with Coverage Reduction	New Missed Lines	%
fishbase/fish_logger.py	1	24.19%
fishbase/fish_common.py	2	89.78%
<!--	Total:	3		-->

Totals
Change from base Build 493:	-0.4%
Covered Lines:	733
Relevant Lines:	821

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 500

• 10 of 15 (66.67%) changed or added relevant lines in 3 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.4%) to 89.281%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
fishbase/fish_logger.py	2	7	28.57%
<!--	Total:	10	15	66.67%	-->

Files with Coverage Reduction	New Missed Lines	%
fishbase/fish_logger.py	1	24.19%
fishbase/fish_common.py	2	89.78%
<!--	Total:	3		-->

Totals
Change from base Build 493:	-0.4%
Covered Lines:	733
Relevant Lines:	821

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 500

• 10 of 15 (66.67%) changed or added relevant lines in 3 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.5%) to 89.268%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
fishbase/fish_logger.py	2	7	28.57%
<!--	Total:	10	15	66.67%	-->

Files with Coverage Reduction	New Missed Lines	%
fishbase/fish_logger.py	1	24.19%
fishbase/fish_common.py	2	89.78%
<!--	Total:	3		-->

Totals
Change from base Build 493:	-0.5%
Covered Lines:	732
Relevant Lines:	820

---

💛 - Coveralls