Add 'composer install' step to vagrant build

[dartajax]

There needs to be a 'composer install' step in the Puppet provisioning the vagrant build

[dartajax]

NOTE: When doing 'composer install', at one point it prompts for github username and password... Here is the following info displayed for that section of the execution:

 - Installing phpunit/phpunit-skeleton-generator (2.0.1)
    Downloading: connection...
Could not fetch https://api.github.com/repos/sebastianbergmann/phpunit-skeleton-generator/zipball/c0eeb18f31893c2f0c387bce84f8a3816a0eacd1, enter your GitHub credentials to go over
 the API rate limit
A token will be created and stored in "/root/.composer/auth.json", your password will never be stored
To revoke access to this token you can visit https://github.com/settings/applications

[dartajax]

It is necessary to provide some parameters as shown below the line. The defaults are provided within the brackets and can be selected by pressing Enter on the keyboard.

---

Some parameters are missing. Please provide them.
database_driver (pdo_mysql):
database_host (127.0.0.1):
database_port (null):
database_name (ilios):
database_user (ilios_user):
database_password (ilios_pass):
mailer_transport (smtp):
mailer_host (127.0.0.1):
mailer_user (null):
mailer_password (null):
locale (en):
secret (ThisTokenIsNotSoSecretChangeIt):
debug_toolbar (true):
debug_redirects (false):
use_assetic_controller (true):

[jrjohnson]

We can get around #789 (comment) easily by creating a default parameter file for vagrant. There is already one for travis.