Update battery plugin to show calculating - OSX

Instantly after removing the charger, I have found that the "AvgTimeToEmpty" value can swing to rediculous values. Apple's current claim is that the max battery life is 12 hours, so any value larger than this is considered a "time is being calculated" value.
Remove mailcatcher from the bundler plugin.

Recommended by @sj26 per https://github.com/sj26/mailcatcher#bundler.
added the linux implementation to the battery plugin
Added dirhistory plugin.

This plugin navigates directory history using ALT-LEFT and ALT-RIGHT.
List pkgs by size
Use zsh's default for ':completion:*:hosts'

The manual configuration of ':completion:*:hosts' causes some problems
(e.g. issue #1337), and misses useful information (especially from
~/.ssh/known_hosts; issue #690 and issue #1009).

The best option appears to be using zsh's default configuration for
':completion:*:hosts'.

While rebasing this for a new pull request (#1498 got closed by accident
and then requests to re-open it got ignored), it also drops the `users
off` setting: completion of user names can be useful, and the commit
adding it (c4434d2) does not state why.
ssh-agent: prevent environment file from flapping

On an OS X laptop, the variable `$HOST` changes a lot depending
on what wifi network you're connected to.  This causes a lot
of `~/.ssh/environment-$HOST` files to be created and
causes multiple ssh-agents to created.

Instead, use `scutil --get ComputerName` to get something
more stable.
add option to show dirty status of current dir
Merge branch 'master' of git://github.com/robbyrussell/oh-my-zsh into dev
Merge pull request #2602 from blueyed/use-default-hosts-completion-2

Use zsh's default for ':completion:*:hosts'
Ignore more users in ssh completion.

Signed-off-by: Mariusz Fik <fisiu@opensuse.org>
Merge pull request #2613 from Fisiu/ignore-ssh-users

Ignore more users in ssh completion.
Merge pull request #2607 from avonderluft/dev

Show svn dirty on current dir, as well as whole working copy
Merge pull request #2603 from docwhat/ssh-agent-hostname

ssh-agent: prevent environment file from flapping
Merge pull request #2574 from thiagowfx/linux-battery

added the linux implementation to the battery plugin
Merge pull request #2549 from brandon-beacher/master

Remove mailcatcher from the bundler plugin.
Merge pull request #2539 from chriswiggins/master

Update battery plugin to show calculating - OSX
Merge pull request #2597 from githubhjs/master

List pkgs by size
Merge pull request #2576 from jeffwilliams/master

Added dirhistory plugin.
Merge branch 'master' of github.com:robbyrussell/oh-my-zsh