ipdevpoll fetches incorrect load average values from Juniper devices

[lunkwill42]

A short spelunking through the code base with a colleague randomly revealed a silly bug in how load average values are collected by our JUNIPER-MIB MibRetriever implementation.

The problem should be obvious from these three lines:

nav/python/nav/mibs/juniper_mib.py

Lines 32 to 34 in b6512a0

	LOAD_AVG_1MIN = "jnxOperating1MinLoadAvg"
	LOAD_AVG_5MIN = "jnxOperating1MinLoadAvg"
	LOAD_AVG_15MIN = "jnxOperating1MinLoadAvg"

The same 1 minute load average value is used and reported as both 1 minute, 5 minute and 15 minute load average values.