Traceback if repo not mounted

[rmanly]

I forgot to mount the share before testing changes for my pull request. :(

$ ./spruce report >> ~/Desktop/spruce_report-2.txt
Traceback (most recent call last):
File "./spruce", line 136, in
main()
File "./spruce", line 33, in main
args.func(args)
File "/Users/ryan/src/forks/Spruce-for-Munki/spruce_tools/report.py", line 305, in run_reports
all_plist = FoundationPlist.readPlist(all_path)
File "/Users/ryan/src/forks/Spruce-for-Munki/spruce_tools/FoundationPlist.py", line 85, in readPlist
raise NSPropertyListSerializationException(errmsg)
spruce_tools.FoundationPlist.NSPropertyListSerializationException: stream had too few bytes in file /Volumes/repo/catalogs/all