FIX: support maprfs (hadoop client hadoop-2.4.1) URL scheme which leaded...

FIX: support maprfs (hadoop client hadoop-2.4.1) URL scheme which leaded pydoop to try to locate  and add a seek(0) to make file reading work.
cf. my initial issue here: https://sourceforge.net/p/pydoop/discussion/990018/thread/e36ee964/

Please check if it doesn't brake anything on other environments. At least on a marpfs all methods open, get, put, ... are working :-)