Remove `locale` config in favour of `site_languages`

Locale configuration during installation is done with two config parameters:
`locale` and `site_languages`, which is excessive. Given that the `locale`
parameter is a simple boolean, its value can be inferred from the value of
`site_languages` parameter.

README.adoc

@@ -35,9 +35,6 @@ Those are global project parameters mandatory to Drupalizer.
 |This env var is defined by Fabric itself, and it's defaut value is True.
 |You can easily pass it to False, addinf --no-pty to your fab command line. Useful in Jenkins jobs.
 
-|_locale_
-|If True, install the site in French.
-
 |===
 
 === Site settings
@@ -88,7 +85,7 @@ Those are global project parameters mandatory to Drupalizer.
 |The Drupal site directory (only for multisite). Default: _default_.
 
 |_site_languages_
-|Translation files you need to download when building new Drupal installation (separate with comma). Default: _fr_.
+|Translation files that must be downloaded when building Drupal and activated during installation (separate with comma). Default: _fr_.
 
 |===
 

default_vars.py

@@ -7,7 +7,6 @@ from fabric.api import env
 
 env.project_name = 'drupalizer-default'
 env.workspace = path.join(path.dirname(__file__), path.pardir)
-env.locale = False
 
 
 # Site

drush.py

@@ -128,7 +128,10 @@ def site_install():
         h.fab_run(role, 'chown {}:{} ./sites'.format(env.apache_user, env.apache_user))
         h.fab_run(role, 'chmod ug+w ./sites/default'.format(env.docker_site_root))
 
-        locale = '--locale="fr"' if env.locale else ''
+        if env.site_languages:
+            locale = '--locale="{}"'.format(env.site_languages)
+        else:
+            locale = ''
 
         h.fab_run(role, 'sudo -u {} drush site-install {} {} --db-url=mysql://{}:{}@{}/{} --site-name="{}" '
                         '--account-name={} --account-pass={} --sites-subdir={} -y'.format(apache, profile, locale,