Fixed LogService vlog_i buffer overflow issue causes by incorrect use of vsnprintf return value.
Reported-by: Leonid Veytser <veytser@ll.mit.edu>
See https://github.com/adjacentlink/emane/issues/2
Added additional check for overflow on timestamp and level buffer insertion.
Merge branch 'feature/logserverbufferoverflow' into develop
See https://github.com/adjacentlink/emane/pull/4