Add ThreadNameFilter from Dropwizard.

This changes the thread name on each request so that log messages a
easier to correlate with access log entries.
Merge branch 'master' into threadname-filter

Conflicts:
	src/java/grails/plugin/lightweightdeploy/ExternalContext.java
Fix unit test for OS X.
Remove accidental commit of .orig
Merge pull request #15 from deverton/threadname-filter

Add ThreadNameFilter from Dropwizard.