Adds logback.xml file to bridge webapp. Points to log file in /var/log/duracloud/bridge.log.
Resolves issue of content properties reader getting stuck in an infinite reading loop (by synchronizing the properties read method and making sure to exit if null values start showing up.) Also skips the snapshot properties file when updating content item properties, since the snapshot properties file is not written to the space. Also fixes a couple email text typos.