SERVER-4345 Add support processing fifo files in mongorestore

Example : `./mongorestore -d test -c foo_dupl <(mongodump -d test -c foo -out - 2>/dev/null | tail -n+2)`
Example (after pull #204) : `./mongorestore -d test -c foo_dupl <(mongodump -d test -c foo -out - 2>/dev/null)`