correct documentation for -b and add -B which actually does what -b said it did
Use && instead of and.
snmp-if-metrics: Add support for low capacity counters
Merge pull request #579 from mduggan/http-check-bytes

http-check: Correct documentation for -b and add -B
Merge pull request #580 from maoe/snmp-if-metrics-low-capacity

snmp-if-metrics: Add support for low capacity counters