Add commonly used filesystem file routines

[fstab50]

FILE COUNT in a directory:

import os

def file_count(directory):
    """
    Returns a count of the number of files in a directory
    """
    count = 0
    for root, dirs, files in os.walk(directory):
        for file in files:
            count = count + 1
    return count

FILE AGE

import datetime, os

def filesystem_age_days(fname=''):
    """Returns the age in days of the file or folder given as a parameter"""
    if not fname:
        return 0    # No files in directory; fname is blank
    st = os.stat(fname)
    dt_modified = datetime.datetime.fromtimestamp(st.st_mtime)
    # calc age
    now = datetime.datetime.now()
    age = convert_dt_seconds((now - dt_modified).seconds)
    return age