Use a better PS1

* Remove the clock;
* Change the symbol from blue to white;
* Change the symbol from dollar to lambda;
* Use single space instead of double space;

Before:

  ~/Code/dotfiles  (ruby-1.9.2-p290)  (master)
  21:04:29 $

After:

  ~/Developer (1.9.3-p327) (master)
  λ
Configure screen using screenrc

The status line will be something like:

  [ Gabriel-Sobrinho ] [ (0*bash)  1 bash  2- bash ] [ 13/01 17:42 ]
Ignore foreman stuff

You can use the .env file to configure environment variables like
RACK_ENV and PORT.
Ignore .ruby-version

This file is similar to .rvmrc and .rbenv-version of rbenv and chruby.
Do not ignore .sass-cache

I'm not sure when but seems like the rails applications do not generate
this artefact anymore.

Anyway, this artefact should be ignored by the rails project and not my
machine.
Recognize gherkin files on ack
Recognize phtml files on ack
Attach homebrew sbin path

I'm not sure why rabbitmq and nginx binaries go there since sbin
"should contain only binaries essential for booting, restoring,
recovering, and/or repairing the system in addition to the binaries in
/bin".
Remove NODE_PATH from environment

Seems like the node formula do not require it to be set anymore.
Do not hardcode the dotfiles location

This will allow to use any location without changing the bash_profile
script.
Append heroku toolbelt path to PATH