Adjustments to support installations without fast_404 with no failures

[fubarhouse]

The following error is produced when this scaffold is used locally where fast_404 is absent.

PHP Fatal error:  Uncaught Error: Call to undefined function cache_get() in /app/docroot/includes/module.inc:762
Stack trace:
#0 /app/docroot/includes/module.inc(962): module_implements('system_theme_in...')
#1 /app/docroot/modules/system/system.module(2514): module_invoke_all('system_theme_in...')
#2 /app/docroot/includes/theme.inc(798): _system_rebuild_theme_data()
#3 /app/docroot/includes/theme.maintenance.inc(57): list_themes()
#4 /app/docroot/includes/bootstrap.inc(2894): _drupal_maintenance_theme()
#5 /app/docroot/includes/errors.inc(179): drupal_maintenance_theme()
#6 /app/docroot/includes/bootstrap.inc(2622): _drupal_log_error(Array, true)
#7 [internal function]: _drupal_exception_handler(Object(Error))
#8 {main}
  thrown in /app/docroot/includes/module.inc on line 762
Drush command terminated abnormally due to an unrecoverable error.       [error]
Error: Uncaught Error: Call to undefined function cache_get() in
/app/docroot/includes/module.inc:762
Stack trace:
#0 /app/docroot/includes/module.inc(962):
module_implements('system_theme_in...')
#1 /app/docroot/modules/system/system.module(2514):
module_invoke_all('system_theme_in...')
#2 /app/docroot/includes/theme.inc(798): _system_rebuild_theme_data()
#3 /app/docroot/includes/theme.maintenance.inc(57): list_themes()
#4 /app/docroot/includes/bootstrap.inc(2894):
_drupal_maintenance_theme()
#5 /app/docroot/includes/errors.inc(179): drupal_maintenance_theme()
#6 /app/docroot/includes/bootstrap.inc(2622):
_drupal_log_error(Array, true)
#7 [internal function]: _drupal_exception_handler(Object(Error))
#8 {main}
  thrown in /app/docroot/includes/module.inc, line 762

To reproduce

1. Clone this repository
2. Copy a downloaded govcms (7) distribution into the docroot directory.
3. Run ahoy build
4. Run ahoy up
5. Run ahoy drush

What this does

• Puts a safeguard in place to prevent including files which may not exist
• Puts a safeguard in place which wraps the initialisation
• Uses code which doesn't require full bootstrap - drupal_get_path or module_exists would have been nice for example - but it wasn't an option without bootstrap.
• Prevents WSOD (white screen of death) and pretty massive fatal errors (as described above) from appearing so the installation screen can occur - or the site can be installed using drush. Currently, the site cannot be installed via UI or drush because of the missing module.

Notes

• Due to architecture this doesn't impact remote sites, but could affect local sites and does affect this project when used vanilla.