Add flag to skip checkKeys if role == master

[oliver006]

can help with reducing load on master nodes - see #931

[codecov]

Codecov Report

Attention: Patch coverage is 70.58824% with 10 lines in your changes missing coverage. Please review.

Project coverage is 80.81%. Comparing base (145ab23) to head (6c8a6ad).

Files with missing lines	Patch %	Lines
exporter/keys.go	64.28%	4 Missing and 1 partial ⚠️
main.go	0.00%	3 Missing ⚠️
exporter/exporter.go	81.81%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #985      +/-   ##
==========================================
- Coverage   80.82%   80.81%   -0.01%     
==========================================
  Files          19       19              
  Lines        2951     2960       +9     
==========================================
+ Hits         2385     2392       +7     
- Misses        456      457       +1     
- Partials      110      111       +1     

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[coveralls]

Pull Request Test Coverage Report for Build 14682261794

Details

• 26 of 34 (76.47%) changed or added relevant lines in 4 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.01%) to 84.608%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
exporter/exporter.go	10	11	90.91%
main.go	0	3	0.0%
exporter/keys.go	10	14	71.43%

Files with Coverage Reduction	New Missed Lines	%
exporter/exporter.go	1	95.34%

Totals
Change from base Build 14555681531:	0.01%
Covered Lines:	2512
Relevant Lines:	2969

---

💛 - Coveralls