(GH-432) Corrected grammar used in output messages

It was noted by Chocolatey User that "awhile" should be "a while".  This has been corrected in this commit.
Merge branch 'PR433'
Created Unit Tests for Install-ChocolateyDesktopLink

- Added Synopsis for Function
- Added Unit Tests for Function
- Added some Debug statements for Function
- Made sure to use new Pester 2 assert syntax
Merge branch 'PR245'
Created new Helper Function to create generic shortcut

- Added Helper Function
- Created Unit Test to verify Function
- Added Synopsis to help with Documentation
- Used new syntax for Pester 2 asserts
Merge branch 'PR238'
0.9.8.24-alpha2
(maint) cleaning up specs to use Describe/Context
(maint) spacing
(GH-427) throw if checksum passed but no file exists
(GH-427) Default to md5 if setting is not sha1
(GH-427) specs for Get-ChecksumValid