@valid_template_whitelist is empty when using array of symbols as view_template_whitelist option

[allomov]

This article says that I can use an array containing either string or symbol as view_template_whitelist. To find out what view_templates can be found is used intersection & between Refinery::Pages.view_template_whitelist and Refinery::Pages.valid_templates('app', 'views', '{pages,refinery/pages}', '*html*'), the last one returns array of string and if you use & the result will return empty array.
Here is simple example to illustrate this:

[:simple, :array] & ['simple', 'array'] # => [] 

[parndt]

Looks good -- thanks!

[parndt]

Merged to cd8d73f

Travis was failing due to some timeout.