3 bug fixes
Added check for request.path to ensure idleFor parameter is processed only for session_security_ping url
Assume a negative idleFor value means 0 to prevent a log out but if the value is negative
Ignore non-integer idleFor values instead of throwing an exception
Styling changes according to PEP8
Fixed PEP8 problems
Merge pull request #3 from yscumc/master

Middleware polishing.