Update README to fix issue #1

@shalecraig reported that gems were not installed
without his use of the `gem ` utility.

These dependencies should be calculated and
handled by `bundler` and should not require user
management.

Stepping through the documentation as a pristine
user, several steps broke that I needed to explain
better.

1.  Have coffee script compiler
1.  Have bundler
1.  Run bundler before you run `rake`

```text
$ pwd
/home/testuser
$ git clone git://github.com/sgharms/Halbert.git
testuser@roma ~ % cd Halbert

(install zsh)
(install rbenv)
(install ruby-build plugin for rbenv)
testuser@roma ~ %  rbenv install 1.9.3-p194

testuser@roma ~ % which ruby
/home/testuser/.rbenv/shims/ruby

testuser@roma ~ % rbenv rehash

testuser@roma ~ % cd Halbert

testuser@roma ~/Halbert % rbenv global 1.9.3-p194
testuser@roma ~/Halbert % rbenv global
1.9.3-p194
testuser@roma ~/Halbert % rbenv local
rbenv: no local version configured for this directory
testuser@roma ~/Halbert % rbenv local 1.9.3-p194
testuser@roma ~/Halbert % rbenv local
1.9.3-p194

testuser@roma ~/Halbert % cat .rbenv-version
1.9.3-p194

testuser@roma ~/Halbert % ruby --version
ruby 1.9.3p194 (2012-04-20 revision 35410) [i686-linux]
testuser@roma ~/Halbert % which ruby
/home/testuser/.rbenv/shims/ruby
testuser@roma ~/Halbert % gem list

*** LOCAL GEMS ***

bigdecimal (1.1.0)
io-console (0.3)
json (1.5.4)
minitest (2.5.1)
rake (0.9.2.2)
rdoc (3.9.4)

testuser@roma ~/Halbert % bundle
zsh: command not found: bundle

( `gem install bundler` )

testuser@roma ~/Halbert % rbenv rehash
testuser@roma ~/Halbert % bundle
Fetching gem metadata from http://rubygems.org/.........
Fetching gem metadata from http://rubygems.org/..
Installing addressable (2.2.6)
Installing mime-types (1.17.2)
Installing nokogiri (1.5.0) with native extensions
Installing rack (1.3.5)
Installing rack-test (0.6.1)
Installing ffi (1.0.11) with native extensions
Installing childprocess (0.2.3)
Installing multi_json (1.0.4)
Installing rubyzip (0.9.5)
Installing selenium-webdriver (2.15.0)
Installing xpath (0.1.4)
Installing capybara (1.1.2)
Installing coffee-script-source (1.1.3)
Installing execjs (1.2.12)
Installing coffee-script (2.2.0)
Installing daemons (1.1.4)
Installing eventmachine (0.12.10) with native extensions
Installing json_pure (1.6.3)
Installing launchy (2.0.5)
Installing rack-protection (1.1.4)
Installing tilt (1.3.3)
Installing sinatra (1.3.1)
Installing evergreen (1.0.0)
Installing rest-client (1.6.7)
Installing term-ansicolor (1.0.7)
Installing heroku (2.16.2)
Installing sass (3.1.11)
Installing temple (0.3.4)
Installing slim (1.0.4)
Installing thin (1.3.1) with native extensions
Using bundler (1.2.1)
Your bundle is complete! Use `bundle show [gemname]` to see where a bundled gem is installed.

testuser@roma ~/Halbert % rake halbert --trace
** Invoke halbert (first_time)
** Invoke compile (first_time)
** Execute compile
.-=* Compiling assets *=-.
** Invoke assets:cs (first_time)
** Execute assets:cs
Converting Coffeescript to Javascript
        ...custom.coffee
rake aborted!
No such file or directory - coffee -c --bare custom.coffee
/home/testuser/Halbert/Rakefile:89:in ``'
testuser@roma ~/Halbert % which coffee
coffee not found

( `apt-get install coffeescript` )

testuser@roma ~/Halbert % rake
.-=* Compiling assets *=-.
Converting Coffeescript to Javascript
        ...custom.coffee
        ...tree.coffee
        ...bear.coffee
Converting SCSS to CSS
        ...custom.css.scss custom.css.css
thin -C prod.yml -R config.ru start
>> Thin web server (v1.3.1 codename Triple Espresso)
>> Maximum connections set to 1024
>> Listening on localhost:4567, CTRL+C to stop

```