README fixes
Merge branch 'master' of github.com:maianess/studentchooser

Conflicts:
	README.md
removed .txt extenions
replace file handling with 'with filename as f' statements
roster class; new/load/save functions implemented
moved student selection funcs to Roster class
moved attendance functions to Roster class
added 'add_to_roster' func (formerly 'update') to Roster class
fixed all functions in 'main' to run with Roster class
changed 'config' file to be 'all_rosters' file, changed naming for code readability
updated README