[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 branch 'master' of github.com:sorin-ionescu/prezto
Revert "[Fix #436] Remove Bombich rsync references"

This reverts commit 20655c8b66907ff3cc879a8cbe7b82173b597e33.
[Fix #436] Update link to Bombich rsync
Rename archive module functions
[Fix #434] Correct ambiguity in the use of the term keymap
[Fix #411] Add Homebrew module
Merge branch 'master' of github.com:sorin-ionescu/prezto
[Fix #452] Squash bugs introduced in fcab2a1
[Fix #459] Correct typos in the dpkg module
Merge branch 'master' of github.com:sorin-ionescu/prezto
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