Weld should log failure to load a class at a higher level than DEBUG

At the moment weld logs failure to load a class at a log level of debug, which is not displayed by default.

Due to the new modular class loading in AS7 these types of errors will become much more frequent, and the user is given no debug information to determine where the problem is. Changing the default log level to DEBUG for org.jboss.weld.Bootstrap is not an option as this is to verbose.