Support list of files for put and get subcommands in mongofiles

This PR implements logic to support a list of supporting arguments, i.e. file names, for mongofiles put and mongofiles get. The intended behavior is as follows:

The following (1) should put the specified files in the remote GridFS filesystem:

mongofiles put first.bson second.bson third.bson

The following (2) should put all files of the form *.bson in the current directory or any of its subdirectories:

mongofiles put */.bson

mongofiles should not evaluate the glob expression logic – the underlying shell should evaluate the glob expression and call mongofiles with a command of the form specified in (1).

Furthermore, the following command should get the specified files from the remote GridFS filesystem:

mongofiles get first.bson second.bson third.bson

The glob interface is not available for `mongofiles ... get` – that should be made available in TOOLS-2668.