Tidy up PrefixedThrowableProxyConverters

Each implementation had a bunch of code copied from the underlying
Logback implementation with the prefixing code hacked in.

Instead, lets just use regular expressions to replace the beginning of
each trace with the prefix.

Also, let's override the "Wrapped by: " text in
`RootCauseFirstThrowableConverter` and display "Causing: " instead, as
it's more intuitive.

Finally, ensure that the ThrowableProxyConverter is correctly
initialized in tests.
Remove a needless static reference

The static method has been imported, no need to explicitly name the
class.
Merge pull request #397 from nicktelford/fix/tidy-logging-prefixed-traces

Tidy up PrefixedThrowableProxyConverters
Upgrade JDBI to 2.50.
Updated release notes

Should be largely complete, but a few smaller changes may have slipped
through the net.
Fixes #398: EOL in tests strings must match those in template files
Merge pull request #400 from kilemensi/issue-398

Fix tests for EOL in Freemarker template files in Windows

Fixes #398.
timezine -> timezone
Merge pull request #401 from jplock/patch-1

timezine -> timezone
updating references and links to use application instead of service
fixed up a few of the code examples to refect the changes to the Environment