Handle multiple ICAO parameters

[SmCTwelve]

Allow requesting METARs from multiple ICAO's by parsing and requesting data for each given ICAO in turn.

e.g.

py metar.py EGPF EGLL

1. Parse into individual request strings; 'EGPF' and 'EGLL'
2. Request METAR for EGPF
3. Request METAR for EGLL
4. Print results, in order.

Extended functionality may include different time ranges for each airport.

py metar.py EGPF 11:00 12:00 EGLL 13:00 15:00

1. Parse into individual requests; 'EGPF 11:00 12:00' and 'EGLL 13:00 15:00'
2. Request METAR for EGPF with startTime=1100 and endTime=1200
3. Request METAR for EGLL with startTime=1300 and endTime=1500
4. Print results, in order.