Added CsomPeoplepicker using webmethod (CSOM)

Added a new peoplepicker control based on the regular peoplepicker. This peoplepicker does not use JSOM to get data but will call a webmethod on the server. The server wil get the data from Sharepoint and return the results in JSON to the client. We needed this in our company because its was not posible to have AppWebs onPremise due to some ADFS troubles. Bert Janssens works at our company and suggested that I upload the code to PNP.