rteval: add miscellaneous global helper functions

Add helper function in misc.py:

expand_cpulist() - expands a string cpu range into a list of
cpu numbers (make sure this is a list of string values)

online_cpus() - return a list of online cpu numbers

cpuinfo() - return a dictionary of dictionaries where the first
index is the core number (as a string) and the second
is the property defined under that core in the /proc/cpuinfo
file.

Signed-off-by: Clark Williams <williams@redhat.com>