Added tokenizeString() joinStrings() to dmtcp::Util.
Removed dmtcp_checkpoint symlink.
Removed {local,remote}Prefix from coordinator.

All processes must have the same prefixDir.
Removed --prefix from dmtcp_launch.
Removed JALIB_UTILITY environment variable.
Added SharedData::getInstallDir().
Updated preparation for dlsym offset env var.
Move FindHelperUtility to Util::getPath.
Use SharedData::installDir() to get dmtcp install dir.

This would allow us to use the current installDir upon restart instead
of using the hardwired one.
Fixed #18: Recalculate plugin paths on restart.