(MAINT) Add Plans Path Exclusion

[RandomNoun7]

The Puppet parser cannot yet handle bolt plan syntax. Without this
exlusion adding plans to a module causes CI to fail in Appveyor because
the default lint checks will fail.

[RandomNoun7]

This change is in coordination with a PR to the PDK templates, to ensure that modules that have plans don't need as many hand crafted changes to the template controlled files in the module after every PDK Update. puppetlabs/pdk-templates#176

[jpogran]

This is pending #271

[codecov-io]

Codecov Report

Merging #270 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #270      +/-   ##
==========================================
+ Coverage   44.37%   44.45%   +0.08%     
==========================================
  Files          11       11              
  Lines         773      776       +3     
==========================================
+ Hits          343      345       +2     
- Misses        430      431       +1

Impacted Files	Coverage Δ
lib/puppetlabs_spec_helper/rake_tasks.rb	46.34% <100%> (+0.26%)	⬆️
...puppetlabs_spec_helper/puppetlabs_spec/matchers.rb	20.83% <0%> (-0.45%)	⬇️
lib/puppetlabs_spec_helper/tasks/check_symlinks.rb	100% <0%> (ø)	⬆️

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