Merge branch 'maint'

Merge branch 'maint'

* maint:
  sslutils: Remove superfluous parenthesis for sslv3 function too
  sslutils: remove superfluous parenthesis
  check_snmp: modified tests
  check_snmp.c: switched DEFAULT_TIMEOUT to DEFAULT_SOCKET_TIMEOUT (provided by utils.h), already used by help description, see issue #1318
  install snmpd on travis tests
  enable libtab on travis builds
  add perl snmp to travis dependencies
  NEWS: Mention check_ups performance data fix
  Fix incorrect performance data thresholds
  check_dhcp: Fix option parsing
  Fixes segfaults when running via monitoring worker (off-by-one)
  travis: fix http test host
  sslutils: Check if OpenSSL supports SSLv3.

Conflicts:
	NEWS
	plugins/sslutils.c