Improvement: Message from babeltrace concerning discarded events needs improvement

Improvement: Message from babeltrace concerning discarded events needs improvement

New output example:

[warning] Tracer discarded 18508 events between [13:07:22.210641404] and [13:07:22.210642166] in trace UUID 857bd6395891954ab9d3defb2aeb98f7, at path: "/home/compudj/lttng-traces/auto-20130323-130705/kernel", within stream id 0, at relative path: "channel0_1". You should consider recording a new trace with larger buffers or with fewer events enabled.

Fixes #469

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>