abstracted out some common reader tests so they can be reused
don't compute standard deviation, we dont need it
reformatted. added some comments
take 'test' out of the helper name so the functions dont get run twice
added NotImplementedError message
use percent difference to compare means, stddevs
allow passing in multiple files to test the scalings
allow ReaderTests subclasses to specify default test files. Added test for get_all_data returns to beginning of file
use a z test for decimated vs undecimated comparison
added tests for a heka reader
implemented heka reader
removed heka reader stuff
Merge pull request #19 from parkin/hekaReader

added Heka reader. Added some base reader tests.