Create Postgres database after install

This follows the current instructions printed by Homebrew.
Install Redis

It is common enough on the thoughtbot client projects I've seen this
year to want to install it on machines by default.
Install watch
* example: watch heroku ps --remote production
Update the logo to point to the assets path.
Update copyright year range through 2013
Remove unnecessary bit in install instructions
Restart shell after mac script finishes

* Assure installed items and env vars apply.
* Fixes https://github.com/thoughtbot/laptop/issues/63.
Manage Heroku CLI with Homebrew

https://github.com/thoughtbot/laptop/pull/67
Mkdir /usr/local for Homebrew if it doesn't exist
Merge pull request #69 from thoughtbot/ctoomey-mkdir-homebrew

Mkdir /usr/local for Homebrew if it doesn't exist
Use rbenv to change Ruby versions

* Use Homebrew consistently for OS programs.
* Use ruby-build to install Rubies.
* Include auto-switching of Ruby in `~/.zlogin`.
* Upgrade Rubygems after Ruby is installed. This is to help avoid common
  Bundler/Psych issues:
  https://github.com/tenderlove/psych/issues/66
* Use newest Bundler version in order to work with latest Rubygems.
* Use rbenv-gem-rehash so the shell automatically picks up binaries
  after installing gems with binaries.
Add new libraries to README
Alphabetize libraries in README
Force gcc-4.2 compiler when installing Ruby

Avoid errors like:

    st.c:520:35: error: implicit conversion loses integer precision:
    'st_index_t' (aka 'unsigned long') to 'int' [-Werror,-Wshorten-64-to-32]
    i = table->num_entries++; ~ ~~~~~~~~~~~~~~~~~~^~

https://github.com/sstephenson/ruby-build/issues/287
Install Hub gem

* Used by Suspenders' `--github organization/project` flag.
* `hub merge http://github.com/organization/project/pulls/123` for
  merging pull requests in open source projects.
* `hub browse` for opening the branch in a web browser.
* `hub pull-request` to create a pull request for the feature branch
  you're working in.
* Lots more.
Install The Silver Searcher instead of Ack

https://github.com/ggreer/the_silver_searcher

* ag searches faster than ack
* ag searches all files by default (but still ignores gitignored files).
  This removes the need for ack's --type-add= options.
Fix rbenv install

Error was:

    command not found: CC=gcc-4.2

* Set shell to Ruby 1.9.3 after installing it to make sure the following
 `gem` commands are using the correct Ruby.
* Use easier-to-read `--no-document` flag.
Begin porting to ubuntu
Debian derivative support for the Laptop script

This implements support for:
* Ubuntu quantal
* Ubuntu precise
* Debian wheezy
Fix OSX zsh environment bug

* This a known bug discussed [here](https://github.com/sorin-ionescu/prezto/issues/381).