Change logging behavior to pass exception object to LOG methods

Throughout the codebase, exceptions are reported by logging e.getStackTrace().toString(). As getStackTrace returns an array and Java's array .toString method just returns the object ID, this means that the stack traces are effectively lost. Instead the exception should be passed to the logger in its original form as the second argument, SLF4J does the right thing with the stack trace.

This problem was tackled in GORA-230 for AccumuloStore. The attached patch corrects all instances of the problem in the current trunk.