bokmann/business_time — pull request #85 by Flink (2014-07-07 20:41:04+00:00)
Title: Fix thread safe issues

Added a local_config when using `BusinessTime::Config#with`. It copies
the current global config to current thread, apply the wanted
modifications and work as expected inside the block.
Calls to `BusinessTime::Config#config` and `BusinessTime::Config#config=`
will return the local_config if it exists.