add whisper-auto-update script

it's like whisper-update, but instead of specifying manual values,
you specify a callback function which gets executed to calculate
the new value
Improve rrd2whisper's handling of rrd files

Take into account the actual retentions in rrds and make whisper
archives similarly. Also allow selection of non-AVERAGE rrd archive
types
Actually display seconds in error message if lower precision archive does not cover time interval.
Print the Full Help message

Print the full help message instead of just the usage message without the options.
Merge pull request #19 from lambdafu/master

Fix precision error message
Merge pull request #19 from lambdafu/master

Fix precision error message
Merge pull request #16 from dieterbe/whisper-auto-update-script

Moved to contrib/ from original request
update print_usage to print_help for all whisper bin scripts
Merge pull request #23 from draco2003/patch-1

Print the full help message in tools
Add initial whisper-auto-resize script and add contrib files to travis tests
Merge pull request #24 from draco2003/whisper-auto-resize

Add initial whisper-auto-resize script
Added README
Added README for rrd2whisper.py
Merge pull request #26 from daniellawrence/master

Added README
Fix a few small tyops from #26
Added relatively comprehensive unit test for whisper.
Moved to class setUp and tearDown. Modified temporary file name to db.wsp.
Improved whisper test cases.
Some code style (primarily) updates to the awesome whisper tests
test_whisper.py: silly pylint updates