RFR: 980: Update log level of thrown exceptions

[Erik Joelsson]

This patch updates (almost) all uses of log.throwing() to log.log() so that we can include any exception in a log message of the appropriate level. This became necessary as we started logging each log message individually to logstash, so the FINER level logs from log.throwing() were no longer included. 

In addition to this, I'm also adding stack_trace and logger_name as fields in the logstash logging entries.

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Commit messages:
 - Log stacktraces at the appropriate level. Include stacktraces and logger name in logstash logs.

Changes: https://git.openjdk.java.net/skara/pull/1132/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1132&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-980
  Stats: 107 lines in 13 files changed: 46 ins; 42 del; 19 mod
  Patch: https://git.openjdk.java.net/skara/pull/1132.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1132/head:pull/1132

PR: https://git.openjdk.java.net/skara/pull/1132