Bump whisper-go revision to fix aggregation (issue #379).
Issue #263 LogfileInput parsing improvements

- Fix the file handle leak in file discovery
- Update the journal to store the location and length of the last record
  (not backwards compatible, existing journal files will fail to load and a new one created)
- Add the regexp parser
- Keep the token parser since there are some performance benefits (10-15%)
over the regexp parser (mainly do to the final conversion from byte array to string)
- Remove the Logline struct and use a pipeline pack instead. This is cleanup and
preparation for the protobuf parser which needs access to the pack and message)
Merge pull request #388 from mozilla-services/issues/379-whisper-bump

Bump whisper-go revision to fix aggregation (issue #379).
Merge pull request #391 from mozilla-services/issue_263

Issue #263 LogfileInput parsing improvements
Generate a reasonable default working directory for SandboxManagerFilter if none is
explicitly specified.
Typo.
Figure sandbox filter file paths relative to the Heka base_dir.
Don't use a separate default working dir for each sbx manager since they'll
namespace the files themselves.
Merge pull request #392 from mozilla-services/features/sandbox-base-dir

Features/sandbox base dir
Merge branch 'dev' into features/multidecoder
Updated toml dependency, removed `CatchAll` option, added `log_sub_errors`
option, removed panic recovery.