Log Message:
Update sysutils/erlang-lager to 3.5.1.

3.5.1 - 15 June 2017

- Doc fix: Missed a curly brace in an example. (#412)
- Feature: Dynamic metadata functions (#392) - It is now possible to
           dynamically add metadata to lager messages. See the "dynamic
           metadata" section above for more information.
- Doc fix: Add information about the "application" placeholder. (#414)

3.5.0 - 28 May 2017

- Bugfix: Support OTP 20 gen_event messages (#410)
- Feature: Enable console output to standard_error.
           Convert to proplist configuration style (like file handler)
           Deprecate previous configuration directives (#409)
- Bugfix: Enable the event shaper to filter messages before they're
          counted; do not count application/supervisor start/stops
          toward high water mark. (#411)
- Docs: Add PR guidelines; add info about the #lager chat room on freenode.

3.4.2 - 26 April 2017

- Docs: Document how to make lager use UTC timestamps (#405)
- Docs: Add a note about our triage cadence.
- Docs: Update lager_syslog URL
- Docs: Document placeholders for error_logger integration (#404)
- Feature: Add hex.pm metadata and full rebar3 support.

3.4.1 - 28 March 2017

- Docs: Added documentation around using lager in the context of elixir \ 
applications (#398)
- Bugfix: Properly expand paths when log_root is set. (#386)
- Policy: Removed R15 from Travis configuration

3.4.0 - 16 March 2017

- Policy: Adopt official OTP support policy. (This is the **last** lager 3.x release
  that will support R15.)
- Test: Fix timeouts, R15 missing functions on possibly long-running tests in \ 
Travis. (#394, #395)
- Feature: capture and log metadata from error_logger messages (#397)
- Feature: Expose new trace filters and enable filter composition (#389)
- Feature: Log crashes from gen_fsm and gen_statem correctly (#391)
- Docs: Typo in badge URL (#390)

3.3.0 - 16 February 2017

- Docs: Fix documentation to make 'it' unambiguous when discussing asychronous
  operation. (#387)
- Test: Fix test flappiness due to insufficient sanitation between test runs \ 
(#384, #385)
- Feature: Allow metadata only logging. (#380)
- Feature: Add an upper case severity formatter (#372)
- Feature: Add support for suppressing start/stop messages from supervisors (#368)
- Bugfix: Fix ranch crash messages (#366)
- Test: Update Travis config for 18.3 and 19.0 (#365)

3.2.4 - 11 October 2016

- Test: Fix dialyzer warnings.

3.2.3 - 29 September 2016

- Dependency: Update to goldrush 0.19

3.2.2 - 22 September 2016

- Bugfix: Backwards-compatibility fix for `{crash_log, undefined}` (#371)
- Fix documentation/README to reflect the preference for using `false`
  as the `crash_log` setting value rather than `undefined` to indicate
  that the crash log should not be written (#364)
- Bugfix: Backwards-compatibility fix for `lager_file_backend` "legacy"
  configuration format (#374)