Bump fern from 0.4.3 to 0.5.5

[dependabot-preview]

Bumps fern from 0.4.3 to 0.5.5.

Changelog

Sourced from fern's changelog.

0.5.5 (2018-03-25)

• Add a log handler for logging into an arbitrary Write object. (thanks [vorner]!)

0.5.4 (2018-02-17)

• Add a log handler which panics on all messages. This can be used in
  test configurations to turn warning or error messages into hard
  errors.
• meta: add test coverage reporting via tarpaulin and coveralls

0.5.3 (2018-02-04)

• Add support for Display::fmt implementations which call the global
  logger via a 'meta-logging-in-format' flag. (thanks [jakunar]!)
  • This is disabled by default, see 'meta' module for more info.

0.5.2 (2018-01-02)

• Re-add compatibility for rust versions 1.16.0+, and add CI testing
  with rustc 1.16.0 to ensure this is kept in the future.
• Add some more general documentation updates and clarity increases.
• Add a CHANGELOG.md which mirrors git tag releases.
• Update documentation links to point to docs.rs rather than custom
  hosted documentation.
• Fix ColoredLevelConfig::default being an inherent method rather than
  an implementation of the Default trait.
• Add direct support for the syslog crate under the "syslog-3"
  feature flag.
  • Add a module worth of documentation for using fern with syslog.

0.5.1 (2017-12-26)

• Re-add support for colored log levels with the 'colored' feature
  • Support for this was accidentally dropped in 0.5.0.
• Fix the ability to run tests on windows, and refactor integration
  tests for developer clarity
• Update documentation for clarity

Short list of changes in 0.5.0:

• Updated from log 0.3 to log 0.4. Both are interoperable, but using
  log 0.4 provides a much cleaner log interface for fern to use
  internally
• Removed fern::FernLog.
• Renamed fern::color::ColoredLogLevelConfig to ColoredLevelConfig
  ... (truncated)

Commits

• 6c9cfe5 Release version 0.5.5
• 608371b Add a test for the new raw writing API
• 0410988 Merge pull request #24 from vorner/box-write-output
• 2498a77 Add output to arbitrary Write objects
• e5a4c5d Release version 0.5.4
• 8639bd1 Update CHANGELOG.
• 53cff04 Add coveralls badge to Cargo.toml
• 0f0dacb Implement a log handler which panics on messages. (#21)
• 5d3847c Update documentation:
• 35c7fae Change source of appveyor badge.
• Additional commits viewable in compare view

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