Install: Fix use of DEBIAN_FRONTEND - `sudo` clears environment

Before executing a command, for security reasons `sudo` clears the
environment, so the value of DEBIAN_FRONTEND was never passed to
apt-get. This was causing the mysql packqge to still prompt for
a value interactively.
Install: Options "-q" (quiet), "-n" (no pull), "-y" (non interactive)

Added several options to the `create-dev-env.sh` script to improve its
ability to be used by another script:

* -y -- non interactive mode (no prompt, proceed immediately)
* -n -- do not attempt to pull edx-platform
* -q -- be more quiet (removes info at beginning & end)

This will be used, in particular, for Vagrant provisioning.
Install: Improves ruby/rvm install - Directly install the right version

The script used to download the latest version of ruby through rvm, then
later on install the one used by the project. Now we directly download
the version of the project when rvm is installed.
Install: Make curl options more consistent, add logging of errors

The options passed to curl were not always the same - added logging of
error (-S) everywhere (was only used for Mac before) and made it quiet
in the rare few cases where it wasn't yet (-s).
Install: Make `apt-get` and `mkvirtualenv` output log friendly

Added options to make the output of `apt-get` and `mkvirtualenv`
friendlier to getting logged. This allows to be more easily recorded in
log files or when the install is performed through utilities - like
Vagrant.
Install: Fix install script freeze (syncdb superuser account creation)

Since the output is passed through tee, when the django admin asks the
user if he would like to create a super user account, it blocks the
install, without even showing the question.

Disabled interactivity for syncdb.
Vagrant: Add support for Vagrant install (`vagrant up`)

Cf README, this adds support to install and setup a dev instance through
Vagrant. The Vagrantfile at the root handles the vagrant commands like
`vagrant up`.

Provisioning is done by the shell script `vagrant-provisionning.sh`,
which is a light wrapper around the `create-dev-setup.sh` which does
most of the job using the standard process, but limiting possible
side-effect by ensuring the environment on which the install is
performed is clean.

Based on an Ubuntu precise 12.04 LTS.
vagrant: Normalize shell script EOL to Unix LF
Vagrant: install edx-platform under /opt

Compatibility with the Filesystem Hierarchy Standard: http://www.pathname.com/fhs/
vagrant: Moves from `/opt/edx-platform` to `/opt/edx/edx-platform`

To allow the vagrant user to create the /opt/edx/[log|data|db] folders
vagrant: Set `$PROJECT_HOME` - `$BASE` was set to the default path

Yarko's `$BASE` patch has been merged and rewritten since
the original pull request was created, resulting in the `$BASE` being
incorrectly set to the default `/home/vagrant/edx_all` by the new code.
vagrant: Update README (QA, link to wiki & disk space requirement)
vagrant: Remove rvm Ubuntu package installation (triggers rvm bug)
vagrant: Windows - Preserve Unix line return format, added extensions
vagrant: Requirement on VirtualBox 4.2.12 for compatibility with Vagrant
vagrant: Prevent git from altering line endings altogether
vagrant: Windows - Exclude README from ws_migration

Windows doesn't differentiate between files with/without executable bit,
so this can't be used to exclude the README file from the migrations to
be executed, when the sources are accessed from a Windows partition.
vagrant: Windows - Bind node_modules to a ext4 partition for symlinks
vagrant: Installation instruction tweaks from Yarko & Windows testing
vagrant: Fix prereqs update when prereqs had been fetched outside of VM