Test update/Fix progress temp save

Edited test to catch readline error. file.py code change in progress
(DOES NOT WORK PROPERLY) so saving it temporarily.
new readline test passes

Changed file.py readline() to always check for a newline. Had to make a
few changes for what went into self._rbuffer in the case where buffer
size was met or exceeded and we found a newline.
Refactoring

Added comments. Removed fifth line from test because it was unnecessary
since the final line could be used instead.
Changelog closes #428