travis: disable tests against groonga-httpd
travis: disable tests against groonga-httpd

Because groonga-httpd doesn't support log_level command. groonga-httpd
creates grn_ctx for each request. So changed log level is also
dropped...

cosmo0920/groonga,komainu8/groonga,komainu8/groonga,naoa/groonga,komainu8/groonga,kenhys/groonga,kenhys/groonga,naoa/groonga,groonga/groonga,cosmo0920/groonga,hiroyuki-sato/groonga,groonga/groonga,kenhys/groonga,groonga/groonga,redfigure/groonga,redfigure/groonga,redfigure/groonga,groonga/groonga,komainu8/groonga,naoa/groonga,hiroyuki-sato/groonga,naoa/groonga,redfigure/groonga,groonga/groonga,naoa/groonga,kenhys/groonga,cosmo0920/groonga,cosmo0920/groonga,kenhys/groonga,hiroyuki-sato/groonga,kenhys/groonga,komainu8/groonga,hiroyuki-sato/groonga,cosmo0920/groonga,groonga/groonga,groonga/groonga,naoa/groonga,naoa/groonga,groonga/groonga,komainu8/groonga,kenhys/groonga,cosmo0920/groonga,cosmo0920/groonga,redfigure/groonga,kenhys/groonga,naoa/groonga,komainu8/groonga,komainu8/groonga,cosmo0920/groonga,redfigure/groonga,redfigure/groonga,hiroyuki-sato/groonga,redfigure/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga