Refactoring following Mark advices + features

Added module header
Tab spacing = 4 characters
Removed ##### comments
Renamed functions as per PEP008
PrintList: list = python keyword therefore should not be used as a
parameter name
UrlTest: try, except, else, (finally)
2 lines between functions (see PEP008)
Shorten lines - max 80 chars
Use os.path.join function to concat file paths
Prefer tuples to lists unless required
Replace string literals with constants
No need for space before :
\ line continuations are unnecessary within function call
Use string.format function rather than old style string replacement %
Use triple-quotes to make long strings more readable
Prefix module level variables with _ (see PEP008)
Avoid variable names < 3 chars in length
Wrap mainline in _main function
Use with keyword to auto close file handlers
Use processing context info class to encapsulate processing state.
Improve screen display
Store missing date in miss_aggregation.list and miss_directories.list
Update README