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 69.69697% with 10 lines in your changes missing coverage. Please review.

Project coverage is 82.10%. Comparing base (7c63842) to head (aab0119).
Report is 3 commits behind head on master.

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	80.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #985      +/-   ##
==========================================
- Coverage   82.11%   82.10%   -0.01%     
==========================================
  Files          18       18              
  Lines        2756     2766      +10     
==========================================
+ Hits         2263     2271       +8     
- Misses        401      402       +1     
- Partials       92       93       +1     

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[coveralls]

Pull Request Test Coverage Report for Build 13758090019

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 25 of 33 (75.76%) changed or added relevant lines in 4 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 85.514%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
exporter/exporter.go	9	10	90.0%
main.go	0	3	0.0%
exporter/keys.go	10	14	71.43%

Files with Coverage Reduction	New Missed Lines	%
exporter/exporter.go	1	95.3%

Totals
Change from base Build 13745567977:	0.02%
Covered Lines:	2373
Relevant Lines:	2775

---

💛 - Coveralls