…roper support of pipelining.

  This optional parameter will enable easier logging of exception information.

- Implement pipeline support for -Message parameter
  This parameter always accepted pipeline input but didn't follow existing PoSh paradigms
  for pipelining. Note that there is no performance benefit to pipelining, but the option is there.

- Add Write-LogHelper.
  This cmdlet is not intended to be used by itself, but instead should support Write-Log. The cmdlet
  performs the actual act of writing to screen/log.

…ception parameter.

  While it was nice to break things up, keeping the actual writing logic in Write-Log will lead
  to better exception information if the Write-* cmdlets fail, because the exception will show
  as originating from Write-Log (which makes sense), instead of Write-LogHelper (which makes less sense).

… in Invoke-SBRestMethod, etc.

…tents.

This commit replaces all (most?) instances of using Write-Log with implicit -Message parameter.
Modified lines were found with the following regex replacement:

    Find   : Write-Log\s([^-])
	Replace: Write-Log -Message $1