title: String filtering with Ax7 oData gives error
body: <p>I am trying to use the Ax7 oData endpoints to search for sales quotations by Name. Using equality works just fine, but the more advanced filter functions gives me errors.</p>
  
  <p>This simple EQ query works OK:
  <a href="http://%20https://myAx7Server/data/SalesQuotationHeaders?$filter=SalesQuotationName%20eq%20&#39;Sparrow%20Retail&#39;" rel="nofollow noreferrer">https://myAx7Server/data/SalesQuotationHeaders?$filter=SalesQuotationName eq 
       'Sparrow Retail'</a></p>
  
  <p>But this query gives me the error "The type 'System.String' for the query operator is not Queryable!"</p>
  
  <p><a href="https://myAx7Server/data/SalesQuotationHeaders?$filter=startswith(SalesQuotationName,&#39;S&#39;)" rel="nofollow noreferrer">https://myAx7Server/data/SalesQuotationHeaders?$filter=startswith(SalesQuotationName,'S')</a></p>
  
  <p>Am I doing something wrong, or is it just that these oData endpoints do not support searching by string?</p>