Changed check to use ammount of used space instead of ammount of free-space to be more alegoric with df-usage. Added a few more test-cases and hardcoded a disk-/dev/sdtest for regressiontesting
added .gitignore
added a somewhat doubiusly named module to check if the systemclock is in syn with ntp
moved the localization of ntpdate outside the run-function since it will probbably not move that often.
Made ntpdrift a bit more resilliant to differing output from ntpdate, perhaps...
Created a 'smarter' True/False class called Pass/Fail
changed exception-type when subclass did not override __isnonzero__
Changed to pass fail and added test-kludge.

Changed the two existing sensors to use Pass Fail isntead of True False
and added a few kludges to enable simple testing from the command-line.