Add a script to gather data via SNMP in the given interval, store it a file
and draw a graph.

Example use:
./snmp_graph.sh -f oids_temp_ip.txt --ip 192.168.1.10
./snmp_graph.sh -f oids_temp.txt --ip 192.168.1.12 --mibs-path "/var/lib/mibs/ietf:../snmpd" --mibs-load WR-SWITCH-MIB"

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>