Make regex more robust for different currency amount transcriptions

[lippytak]

Discovered during the GTR2014.

Our regex should cover the following cases:

• 64 cents > $0.64
• $1 and $.95 > $1.95
• $.13 > $0.13
• $0 and 36 cents > $0.36

@daguar filter the transcription spreadsheet for 'error_type' == 'senseless-cents' for the full list.