Removed the default values of the parameter ExcludeTag in favor of using opt-in

[johlju]

• Removed the default values of the parameter ExcludeTag in favor of using
  opt-in. Default is that those tests are opt-out, and must be opt-in (issue Remove default values of ExcludeTag parameter in favor of opt-in #274).
• Excluding tag 'Examples' when calling Invoke-AppveyorTestScriptTask since
  this repository will never have examples.

Fixes #274

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This change is 

[codecov-io]

Codecov Report

Merging #277 into dev will decrease coverage by <1%.
The diff coverage is n/a.

@@         Coverage Diff         @@
##            dev   #277   +/-   ##
===================================
- Coverage    72%    72%   -1%     
===================================
  Files        12     12           
  Lines      1523   1522    -1     
  Branches      2      2           
===================================
- Hits       1109   1108    -1     
  Misses      412    412           
  Partials      2      2

[johlju]

Tested OK here:

CertificateDsc (using -ExcludeTag @()): https://ci.appveyor.com/project/johlju/certificatedsc/build/2.3.27.0
PSDscResource (not using ExcludeTag): https://ci.appveyor.com/project/johlju/psdscresources/build/2.4.98.0#L1270

[PlagueHO]

Good stuff @johlju -

Reviewed 2 of 2 files at r1.
Reviewable status: 1 of 4 files reviewed, all discussions resolved (waiting on @PlagueHO)