VMware Plugin: Various improvements.

VMware Plugin: Various improvements.

Made all changes requested by Florian Forster

- Removed trailing white spaces in configure.in, src/collectd.conf.pod, src/vmware.c
- Removed unused plugin_vmware variable from configure.in
- Removed unneeded include statements for stdarg.h, stdio.h, dlfcn.h
- Changed include for vmGuestLib.h to use angle brackets instead of double quotes
- Changed global variable VMGuestLibHandle to static
- Changed printf errors to use ERROR() macro
- Changed variable names to follow the normal C / collectd naming schema, e.g. "elapsed_ms" and "cpu_used_ms".

Rebased on top of Edward Muller's commit. --octo