Fix for LOGBACK-875

Prevent logging on an interrupted thread from shutting down prudent file
appenders due to a FileLockInterruptedException
Merge pull request #218 from nemecec/master

Fix for Prudent FileAppender and thread interruptions (LOGBACK-875)
Add release note for LOGBACK-875 fix
Proposal: Code Enforcement

Updated codeStyle.xml to version 12

Added java-formatter-plugin which will enforce code style formatting on
java code.  It is turned off as it affects code beyond what I want to
touch.  Proposal is that if this is accepted and used, a one time
cleanup should be done by project owners to their liking as there may be
inconsistencies in the codeStyle.xml as compared to the actual code
base.  Rather than introducing that level of changes, I felt this would
be better done in that fashion.