[Fix #437] Always set $TMPDIR
Do not substitute /tmp since $TMPDIR is always set
Add the RubyGems bin directory to PATH on other Unix systems

Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
[Fix #436] Remove Bombich rsync references
Merge remote-tracking branch 'upstream/master'

* upstream/master:
  [Fix #436] Remove Bombich rsync references
  Add the RubyGems bin directory to PATH on other Unix systems
  Do not substitute /tmp since $TMPDIR is always set
  [Fix #437] Always set $TMPDIR