SoX doesn't seem to like scientific notation

[mcartwright]

Pysox needs to format its floats to not be scientific notation when formatting arguments for SoX, otherwise SoX seems to choke. I received

SoxError: Stdout: Stderr: sox FAIL pad: usage: {length[@position]}

when pysox was calling SoX with these arguments:

['sox', '-D', '-V2', u'../data/raw/scaper_audio/siren_wailing/5_siren_police.wav', '-c', '1', '/var/folders/xv/6nccdc7151j71bhvzlrvjhqm0000gp/T/tmpYCzbyz.wav', 'rate', '-h', '44100', 'trim', '0', '6.501565999', 'fade', 'q', '0.01', 'reverse', 'fade', 'q', '0.01', 'reverse', 'norm', '-7.36679718537', 'pad', '3.498434', '1.00000008274e-09']

Note the '1.00000008274e-09' at the end. When this number was changed to '0.00000000100000008274', this error went away, and when changed to a different sci notation number, e.g. '1.0e-3', the problem persisted.

[mcartwright]

(change the occurrences of '{}'.format in your code that expect floats to '{:f}'.format)