Automatic trimming (beginning or end) of submissions to reduce length and remove noise

[kmaclean]

some audio (especially VoxForgeIVR submissions) has clicks of pops at the end (usually) and sometimes at the beginning... need some way to flag a submission that has this problem and trim 1/4 second off the beginning and end of a recording.

In addition, some submissions (especially VoxForgeIVR) have to much silence at the beginning and end of the recording, need to trim this excess silence off -since with WAV format, this silence takes up space (likely not so much and issue with FLAC)