Description of problem:
In Horizon, SSL related options are not configure properly

After deployment, some parameters in horizon required for SSL deployment are
not configured properly.

/var/lib/config-data/puppet-generated/horizon/etc/openstack-dashboard/local_settings
------
# If Horizon is being served through SSL, then uncomment the following two
# settings to better secure the cookies from security exploits

#CSRF_COOKIE_SECURE = True
#SESSION_COOKIE_SECURE = True
-----

HorizonSecureCookies is set as True in my template file, and I expect that 
these parameters should be configured, but something is wrong.

-----
$ grep HorizonSecureCookies -B 1 templates/enable-tls.yaml
parameter_defaults:
  HorizonSecureCookies: True
------

If the configuration is set by ExtraConfig, it works well
~~~
  ControllerExtraConfig:
    horizon::secure_cookies: True

~~~

Version-Release number of selected component (if applicable):
current openstack-tripleo-heat-templates.

How reproducible:
Everytime

Steps to Reproduce:
1. Add the configuration to the environment file.
~~~
parameter_defaults:
  HorizonSecureCookies: True
~~~
2. Deploy Overcloud.
3. Check local_settings of horizon in Controller nodes.

Actual results:
Expected values are not set to the parameters by 'HorizonSecureCookies: True'

Expected results:
Required parameters are configured.

Additional info:

In puppet/services/horizon.yaml, the parameter is passed to 'horizon::secure_cookies:'.

~~~
    129           horizon::secure_cookies: {get_param: [HorizonSecureCookies]}
~~~

But the way to pass it looks strange. The parameter, HorizonSecureCookies is defined as boolean.
However, it is passed as a list to secure_cookies in the line.
Following modification might resolve the issue.

~~~
    129           horizon::secure_cookies: {get_param: HorizonSecureCookies}
~~~