Search-Splunk fails when starting search with generating command (i.e. a pipe)

Context: http://answers.splunk.com/answers/128108/splunk-search-with-powershell-sdk-using-inputlooup

Fix proposal (looks legit): 

> Perhaps we just need to update line 85 of https://github.com/splunk/splunk-reskit-powershell/blob/master/Source/Splunk/Splunk-Search/Splunk-Search.psm1 with a conditional that only adds "search" to the pipeline if the first character isn't a "|"?
