Update snmp__df.in

Handle large partitions
ChangeLog: 2.1.5
Merge branch 'pr/151'

Conflicts:
	plugins/node.d/snmp__df.in
cgi/html: fix test in rendering special pages

The test is reversed
Merge branch 'fix-goto' into devel
cgi/html: explicit the comment
Merge branch 'master' into devel
ChangeLog: 2.1.6