Minorly adjusted the recording metadata file format
In the recording metadata files, we now separate each logical section of
metadata by two blank lines. So, it goes:
1. the PCAP file URL
2. two blank lines
3. all answer SDP, each separated by one blank line
4. two blank lines
5. start timestamp
6. end timestamp (no blank line in between)
7. the rest of the file is unstructured metadata (any number of lines)