logstreamer: vet fixes

Fix the following vet reports:

logstreamer/filehandling.go:327: arg l.logfiles for printf verb %s of wrong type: logstreamer.Logfiles
logstreamer/filehandling.go:481: arg newLogfiles for printf verb %s of wrong type: logstreamer.Logfiles
logstreamer/reader.go:94: arg l.SeekPosition for printf verb %s of wrong type: int64
pipeline: vet fix

Fix the following vet report:

pipeline/config.go:560: struct field tag `toml:use_framing"` not compatible with reflect.StructTag.Get
plugins/graphite: vet fix

Fix the following vet report:

plugins/graphite/whisper.go:159: wrong number of args for format in Errorf call: 1 needed but 2 args
plugins/irc: vet fixes

Fix the following vet reports:

plugins/irc/irc_output.go:476: arg output.TimeBeforeRejoin for printf verb %s of wrong type: uint
plugins/irc/irc_output_test.go:382: arg ircOutput.TimeBeforeRejoin for printf verb %s of wrong type: uint
plugins/kafka: vet fixes

Fix the following vet reports:

plugins/kafka/kafka_input_test.go:104: possible formatting directive in Fatal call
plugins/kafka/kafka_input_test.go:196: possible formatting directive in Fatal call
plugins/process: vet fix

Fix the following vet report:

plugins/process/process_input.go:104: struct field tag `toml: trim` not compatible with reflect.StructTag.Get
plugins/statsd: vet fixes

Fix the following vet reports:

plugins/statsd/stat_filter.go:122: arg stat for printf verb %s of wrong type: github.com/mozilla-services/heka/pipeline.Stat
plugins/statsd/statsd_input.go:136: arg stat for printf verb %s of wrong type: github.com/mozilla-services/heka/pipeline.Stat
plugins/udp: vet fixes

Fix the following vet reports:

plugins/udp/udp_input.go:83: no formatting directive in Errorf call
plugins/udp/udp_input.go:167: no formatting directive in Errorf call
sandbox/lua: vet fix

Fix the following vet report:

sandbox/lua/lua_sandbox_test.go:756: arg 1e9 for printf verb %s of wrong type: float64
Merge pull request #1212 from ceh/vet-fixes

vet fixes
Added ability to specify disk buffer size in TCOutput plugin. Fixes #1110