Merge pull request #22 from MWilkinson/master

Updates to SNMP sync code for Bugs #871/#975
add missing commas to $known_switches array
renderEditRackForm: display location parents in the row list (#993)
SNMPsync additions for HP ProCurve 2810-48G J9022A (#767)
Cisco WS-C4948 switch port definitions update (#977)
Addition of Cisco C3560Gv2-48T
Added Cisco 2590SX-24 to snmpsync (#991)